Nsd
Monthly
Stack-based buffer overflow in NLnet Labs NSD's zone-file RDATA parser allows an attacker with the ability to supply a crafted primary zone file to perform out-of-bounds stack writes, including overwriting a callback function pointer that is invoked immediately after parsing, which can lead to arbitrary code execution. The vulnerable path requires direct ingestion of a specially formatted zone file; NSD-generated zone files, including those for secondary zones received by transfer, are not formatted in the triggering way and will not exploit the flaw. No public exploit code or confirmed active exploitation is identified in the available intelligence, and the assessed vector requires low privileges (PR:L) through local or zone-supply access rather than ordinary remote DNS queries.
Loading a crafted zone file into NLnet Labs NSD can overflow a stack buffer and overwrite up to 191 bytes with attacker-controlled data, which can corrupt control flow in the name server process and lead to code execution or a crash. The trigger is a HIP resource record whose RDATA is filled to (or near) its size limit and which also carries a second dname RDATA field, the HIP Rendezvous server; the bug lives in zone-file parsing, so it is not reachable through ordinary DNS query traffic, and zones NSD writes out itself - including secondary zones learned via zone transfer - are not formatted in the vulnerable way. Exploitation therefore requires the attacker to control zone-file content fed directly to NSD, for example through an operator-controlled provisioning or automation pipeline; no public exploit code was identified at time of analysis, and the vendor's CVSS 4.0 vector (AV:N/AC:L/PR:L/UI:N, score 8.7) overstates practical remote risk relative to the assessed CVSS:3.1 vector AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (7.8 High). Authentication is required per the supplied vectors (PR:L), which corresponds in practice to a low-privileged position able to supply zone-file content to the daemon.
A stack-based buffer overflow in NLnet Labs NSD's parsing of SVCB/HTTPS resource records allows an attacker who can supply a crafted zone file to corrupt memory and potentially achieve arbitrary code execution. The flaw is triggered when the RDATA is filled to the wire-format limit and an ECH parameter overflows the stack, after which the base64 decoder can write attacker-controlled data of unlimited size. Exploitation requires that the crafted zone file be fed directly to NSD; zone files written by NSD itself (e.g., secondary zones) are not affected. The attacker must control or inject into the zone-provisioning path, such as a multi-tenant zone-submission pipeline, and authentication requirements are low-privileged per the CVSS vector (PR:L). No public exploit or in-the-wild exploitation has been identified at time of analysis.
Stack-based buffer overflow in NLnet Labs NSD is triggered when the daemon parses a zone file containing base64 data split into chunks of three characters or fewer, causing the token length calculation to yield zero bytes and letting an attacker overwrite up to 64K of stack memory with attacker-controlled data, with likely code-execution impact. Our independent assessment rates this CVSS 3.1 AV:L/AC:L/PR:L/UI:N with High confidentiality, integrity and availability impact, reflecting that the attacker must control zone-file content fed directly to NSD (PR:L, i.e., write/submit access to the zone input path) - it is not reachable through normal DNS queries and does not affect zone files NSD generates itself, such as zones for which the instance is secondary. The vendor rates it CVSS 4.0 8.7 (High) with AV:N/PR:L; patch availability is not confirmed in the provided data, and no public exploit code or CISA KEV activity was identified at time of analysis.
NSD's proxy protocol port fails to re-evaluate BLOCKED access control list entries on the second DNS query sent over a kept-open TCP or TLS connection, allowing a remote unauthenticated attacker to bypass ACL denials that should have blocked the request. NLnet Labs reported this against all NSD versions (CPE wildcard scope), classifying it under CWE-290 as an authentication bypass by spoofing. No public exploit code has been identified at time of analysis, but the bypass mechanic - sending a query twice on the same persistent connection - is mechanically trivial once the proxy protocol port is reachable.
NSD authoritative DNS server crashes serve child processes when receiving a crafted DNS message containing exactly 17 DNS Cookie options with a UDP payload size of 512 bytes, triggering a reachable assertion (CWE-617). This condition exists exclusively in debugging and non-release build types - standard production release builds are immune. Remote unauthenticated attackers can continuously respawn-crash serve children to severely degrade or fully deny DNS resolution service; no public exploit has been identified and the vulnerability is not listed in CISA KEV at time of analysis.
IP range-based access control in NLnet Labs NSD is silently broken on little-endian systems due to an endianness mismatch in the range comparison logic. Both IPv4 and IPv6 addresses are compared as unsigned 32-bit integers using host byte order, while the actual stored values are in network byte order (big-endian), causing comparisons to produce incorrect results on the dominant x86/x86-64/ARM-LE server platforms. The practical consequence is a bidirectional access control bypass: operators relying on hyphen-range ACL syntax may inadvertently permit unauthorized IP addresses to access restricted DNS operations (such as zone transfers) while simultaneously denying legitimate clients. No public exploit has been identified at time of analysis, but the flaw is fully deterministic and requires no special attacker capability beyond network reachability.
Zone-transfer authentication bypass in NLnet Labs NSD allows unauthorized secondaries to obtain full zone contents without presenting the required TLS client certificate. Although a provide-xfr rule specifies a tls-auth-name (mandating client-certificate authentication), NSD only enforces this on the dedicated tls-auth-port; requests arriving over plain TCP on the regular port or over TLS on the regular tls-port are served when the remaining provide-xfr conditions match, defeating mutual-TLS access control. Reported by NLnet Labs with CVSS 4.0 8.2; no public exploit identified at time of analysis and not listed in CISA KEV.
Stack buffer overflow in NSD 4.14.0 (NLnet Labs authoritative DNS server) allows a party able to introduce zone data to overwrite up to 111 attacker-controlled bytes on the stack when a specially crafted APL resource record - carrying an adflength larger than the address family permits - is serialized as the zone is written to disk. Per the CVSS 4.0 vector (PR:L), exploitation requires low privileges and yields high integrity and availability impact, consistent with memory corruption leading to crash or potential code execution. There is no public exploit identified at time of analysis and the issue is not listed in CISA KEV.
Remote denial-of-service in NLnet Labs NSD (authoritative DNS name server) version 4.13.0 and later allows an unauthenticated attacker to crash the server process by exploiting a heap use-after-free in the TLS error-logging path. By sending a DNS query over a DNS-over-TLS (DoT) connection and closing the socket before reading the response, an attacker triggers the freed-memory access trivially; no public exploit identified at time of analysis, and the issue is not in CISA KEV. The CVSS 4.0 score of 8.7 reflects high availability impact with no confidentiality or integrity exposure.
Heap overflow in NLnet Labs NSD allows a malicious or compromised zone primary to corrupt memory on a secondary (slave) NSD instance by sending an AXFR transfer containing a crafted SVCB resource record. An rdata size of 65512 causes a uint16_t length variable used for RR allocation to wrap (total size exceeds 65535), producing an undersized buffer and a controlled out-of-bounds write of up to 65509 bytes - an RCE-class primitive (CWE-190 integer overflow leading to heap overflow). No public exploit identified at time of analysis, but the controlled write and remote network vector (CVSS 4.0 base 8.7) make this a high-priority patch for any operator running NSD as a secondary.
TCP window throttling in NLnet Labs NSD allows any unauthenticated remote attacker to crash individual serve child processes by deliberately shrinking the TCP receive window to near-zero after issuing a DNS query over TCP, triggering an integer underflow (CWE-191). By repeating this pattern continuously, the attacker can deny all TCP-based DNS service from the affected NSD instance. No public exploit code has been identified at time of analysis, and the CVSS 4.0 score of 6.9 reflects moderate availability impact with zero confidentiality or integrity exposure.
NSD before 4.1.11 allows remote DNS master servers to cause a denial of service (/tmp disk consumption and slave server crash) via a zone transfer with unlimited data. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
query.c in NSD 3.0.x through 3.0.8, 3.1.x through 3.1.1, and 3.2.x before 3.2.12 allows remote attackers to cause a denial of service (NULL pointer dereference and child process crash) via a crafted. Rated medium severity (CVSS 5.0), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.
Stack-based buffer overflow in NLnet Labs NSD's zone-file RDATA parser allows an attacker with the ability to supply a crafted primary zone file to perform out-of-bounds stack writes, including overwriting a callback function pointer that is invoked immediately after parsing, which can lead to arbitrary code execution. The vulnerable path requires direct ingestion of a specially formatted zone file; NSD-generated zone files, including those for secondary zones received by transfer, are not formatted in the triggering way and will not exploit the flaw. No public exploit code or confirmed active exploitation is identified in the available intelligence, and the assessed vector requires low privileges (PR:L) through local or zone-supply access rather than ordinary remote DNS queries.
Loading a crafted zone file into NLnet Labs NSD can overflow a stack buffer and overwrite up to 191 bytes with attacker-controlled data, which can corrupt control flow in the name server process and lead to code execution or a crash. The trigger is a HIP resource record whose RDATA is filled to (or near) its size limit and which also carries a second dname RDATA field, the HIP Rendezvous server; the bug lives in zone-file parsing, so it is not reachable through ordinary DNS query traffic, and zones NSD writes out itself - including secondary zones learned via zone transfer - are not formatted in the vulnerable way. Exploitation therefore requires the attacker to control zone-file content fed directly to NSD, for example through an operator-controlled provisioning or automation pipeline; no public exploit code was identified at time of analysis, and the vendor's CVSS 4.0 vector (AV:N/AC:L/PR:L/UI:N, score 8.7) overstates practical remote risk relative to the assessed CVSS:3.1 vector AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (7.8 High). Authentication is required per the supplied vectors (PR:L), which corresponds in practice to a low-privileged position able to supply zone-file content to the daemon.
A stack-based buffer overflow in NLnet Labs NSD's parsing of SVCB/HTTPS resource records allows an attacker who can supply a crafted zone file to corrupt memory and potentially achieve arbitrary code execution. The flaw is triggered when the RDATA is filled to the wire-format limit and an ECH parameter overflows the stack, after which the base64 decoder can write attacker-controlled data of unlimited size. Exploitation requires that the crafted zone file be fed directly to NSD; zone files written by NSD itself (e.g., secondary zones) are not affected. The attacker must control or inject into the zone-provisioning path, such as a multi-tenant zone-submission pipeline, and authentication requirements are low-privileged per the CVSS vector (PR:L). No public exploit or in-the-wild exploitation has been identified at time of analysis.
Stack-based buffer overflow in NLnet Labs NSD is triggered when the daemon parses a zone file containing base64 data split into chunks of three characters or fewer, causing the token length calculation to yield zero bytes and letting an attacker overwrite up to 64K of stack memory with attacker-controlled data, with likely code-execution impact. Our independent assessment rates this CVSS 3.1 AV:L/AC:L/PR:L/UI:N with High confidentiality, integrity and availability impact, reflecting that the attacker must control zone-file content fed directly to NSD (PR:L, i.e., write/submit access to the zone input path) - it is not reachable through normal DNS queries and does not affect zone files NSD generates itself, such as zones for which the instance is secondary. The vendor rates it CVSS 4.0 8.7 (High) with AV:N/PR:L; patch availability is not confirmed in the provided data, and no public exploit code or CISA KEV activity was identified at time of analysis.
NSD's proxy protocol port fails to re-evaluate BLOCKED access control list entries on the second DNS query sent over a kept-open TCP or TLS connection, allowing a remote unauthenticated attacker to bypass ACL denials that should have blocked the request. NLnet Labs reported this against all NSD versions (CPE wildcard scope), classifying it under CWE-290 as an authentication bypass by spoofing. No public exploit code has been identified at time of analysis, but the bypass mechanic - sending a query twice on the same persistent connection - is mechanically trivial once the proxy protocol port is reachable.
NSD authoritative DNS server crashes serve child processes when receiving a crafted DNS message containing exactly 17 DNS Cookie options with a UDP payload size of 512 bytes, triggering a reachable assertion (CWE-617). This condition exists exclusively in debugging and non-release build types - standard production release builds are immune. Remote unauthenticated attackers can continuously respawn-crash serve children to severely degrade or fully deny DNS resolution service; no public exploit has been identified and the vulnerability is not listed in CISA KEV at time of analysis.
IP range-based access control in NLnet Labs NSD is silently broken on little-endian systems due to an endianness mismatch in the range comparison logic. Both IPv4 and IPv6 addresses are compared as unsigned 32-bit integers using host byte order, while the actual stored values are in network byte order (big-endian), causing comparisons to produce incorrect results on the dominant x86/x86-64/ARM-LE server platforms. The practical consequence is a bidirectional access control bypass: operators relying on hyphen-range ACL syntax may inadvertently permit unauthorized IP addresses to access restricted DNS operations (such as zone transfers) while simultaneously denying legitimate clients. No public exploit has been identified at time of analysis, but the flaw is fully deterministic and requires no special attacker capability beyond network reachability.
Zone-transfer authentication bypass in NLnet Labs NSD allows unauthorized secondaries to obtain full zone contents without presenting the required TLS client certificate. Although a provide-xfr rule specifies a tls-auth-name (mandating client-certificate authentication), NSD only enforces this on the dedicated tls-auth-port; requests arriving over plain TCP on the regular port or over TLS on the regular tls-port are served when the remaining provide-xfr conditions match, defeating mutual-TLS access control. Reported by NLnet Labs with CVSS 4.0 8.2; no public exploit identified at time of analysis and not listed in CISA KEV.
Stack buffer overflow in NSD 4.14.0 (NLnet Labs authoritative DNS server) allows a party able to introduce zone data to overwrite up to 111 attacker-controlled bytes on the stack when a specially crafted APL resource record - carrying an adflength larger than the address family permits - is serialized as the zone is written to disk. Per the CVSS 4.0 vector (PR:L), exploitation requires low privileges and yields high integrity and availability impact, consistent with memory corruption leading to crash or potential code execution. There is no public exploit identified at time of analysis and the issue is not listed in CISA KEV.
Remote denial-of-service in NLnet Labs NSD (authoritative DNS name server) version 4.13.0 and later allows an unauthenticated attacker to crash the server process by exploiting a heap use-after-free in the TLS error-logging path. By sending a DNS query over a DNS-over-TLS (DoT) connection and closing the socket before reading the response, an attacker triggers the freed-memory access trivially; no public exploit identified at time of analysis, and the issue is not in CISA KEV. The CVSS 4.0 score of 8.7 reflects high availability impact with no confidentiality or integrity exposure.
Heap overflow in NLnet Labs NSD allows a malicious or compromised zone primary to corrupt memory on a secondary (slave) NSD instance by sending an AXFR transfer containing a crafted SVCB resource record. An rdata size of 65512 causes a uint16_t length variable used for RR allocation to wrap (total size exceeds 65535), producing an undersized buffer and a controlled out-of-bounds write of up to 65509 bytes - an RCE-class primitive (CWE-190 integer overflow leading to heap overflow). No public exploit identified at time of analysis, but the controlled write and remote network vector (CVSS 4.0 base 8.7) make this a high-priority patch for any operator running NSD as a secondary.
TCP window throttling in NLnet Labs NSD allows any unauthenticated remote attacker to crash individual serve child processes by deliberately shrinking the TCP receive window to near-zero after issuing a DNS query over TCP, triggering an integer underflow (CWE-191). By repeating this pattern continuously, the attacker can deny all TCP-based DNS service from the affected NSD instance. No public exploit code has been identified at time of analysis, and the CVSS 4.0 score of 6.9 reflects moderate availability impact with zero confidentiality or integrity exposure.
NSD before 4.1.11 allows remote DNS master servers to cause a denial of service (/tmp disk consumption and slave server crash) via a zone transfer with unlimited data. Rated high severity (CVSS 7.5), this vulnerability is remotely exploitable, no authentication required, low attack complexity. No vendor patch available.
query.c in NSD 3.0.x through 3.0.8, 3.1.x through 3.1.1, and 3.2.x before 3.2.12 allows remote attackers to cause a denial of service (NULL pointer dereference and child process crash) via a crafted. Rated medium severity (CVSS 5.0), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.