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NSD CVE-2026-12246

| EUVDEUVD-2026-39184 HIGH
Classic Buffer Overflow (CWE-120)
2026-06-25 NLnet Labs GHSA-xgm5-85mh-3559
Buffer Overflow Nsd Red Hat Suse
7.2
CVSS 4.0 · Vendor: NLnet Labs
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Severity by source

Vendor (NLnet Labs) PRIMARY
7.2 HIGH
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
8.1 HIGH

Attacker must control zone content so PR:L; network-reachable serialization path AV:N/AC:L; stack overwrite corrupts/crashes giving I:H and A:H with no disclosure (C:N).

3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
4.0 AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
SUSE
HIGH
qualitative
Red Hat
8.0 HIGH
qualitative

Primary rating from Vendor (NLnet Labs).

CVSS VectorVendor: NLnet Labs

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
X

Lifecycle Timeline

2
Patch available
Jun 25, 2026 - 08:01 EUVD
Analysis Generated
Jun 25, 2026 - 07:00 vuln.today

DescriptionCVE.org

NSD version 4.14.0 introduced a bug where a specially crafted APL RR, with an adflength larger than permitted for the address family will overwrite the stack when the zone is written to disk, with a maximum of 111 attacker controlled bytes.

AnalysisAI

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. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Gain ability to supply zone data (PR:L)
Delivery
Craft APL RR with oversized afdlength
Exploit
Deliver record into NSD-served zone
Execution
NSD serializes zone to disk
Persist
Overflow stack with ≤111 bytes
Impact
Crash or corrupt NSD process
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Vulnerability AssessmentAI

Exploitation Exploitation requires the attacker to get a malformed APL (Address Prefix List) resource record - one whose afdlength exceeds the maximum permitted for its declared address family - accepted into a zone that NSD 4.14.0 serves, and the overflow triggers specifically when that zone is written to disk. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment Signals are moderately consistent rather than alarming. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker who can influence the contents of a zone served by NSD 4.14.0 - for example a malicious or compromised primary feeding a secondary, or an actor able to inject records through a zone-management interface - crafts an APL resource record with an afdlength larger than its address family permits. When NSD writes that zone to disk, the oversized address data overflows a stack buffer with up to 111 attacker-controlled bytes, crashing the daemon or potentially corrupting the stack toward code execution. …
Remediation Upgrade NSD to the fixed release published by NLnet Labs as referenced in the advisory at https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-12246.txt; the input data does not contain a confirmed exact fix version, so released patched version is not independently confirmed and the precise target version should be read from that advisory before deploying. … Detailed patch versions, workarounds, and compensating controls in full report.
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Recommended ActionAI

24 hours: Identify all systems running NSD 4.14.0 and audit zone data update sources (automated scripts, APIs, manual imports). …

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Threat intelligence, references, and detailed analysis are available after sign-in.

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Same weakness CWE-120 – Classic Buffer Overflow

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Vendor StatusVendor

SUSE

Severity: Important

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CVE-2026-12246 vulnerability details – vuln.today
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