EUVD-2026-80766
GHSA-h634-6r6v-4pg6
Severity by source
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Remote unauthenticated single crafted DoH request with no user interaction; NULL-pointer dereference aborts named for an availability-only impact, no C/I effect.
Primary rating from Vendor (isc).
CVSS VectorNVD
Lifecycle Timeline
2DescriptionNVD
An attacker can cause named to abort by sending a crafted DNS-over-HTTPS request with a cryptographically invalid SIG(0) record, and then closing the transport connection prematurely. This issue affects BIND 9 versions 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, and 9.20.9-S1 through 9.20.27-S1.
AnalysisAI
Unauthenticated remote attackers can abort the named process in BIND 9 by sending a crafted DNS-over-HTTPS request that carries a cryptographically invalid SIG(0) record and then prematurely closing the transport connection, producing a null pointer dereference (CWE-476) that terminates the server. Affected versions are 9.20.0 through 9.20.27, 9.21.0 through 9.21.25, and the 9.20.9-S1 through 9.20.27-S1 subscription branch; the assessed CVSS v3.1 vector is AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (7.5), meaning no authentication or user interaction and availability-only impact. …
Unlock full vulnerability intelligence
- Risk assessment & exploitation conditions
- Attack chain visualization
- Remediation with exact patch versions
- Threat intelligence from 22 sources
- Personal watchlist & email alerts
Free forever · No credit card required
Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Requires the named instance to have the DNS-over-HTTPS (DoH) transport enabled and to process SIG(0)-signed DNS messages, since the trigger is a DoH request containing a cryptographically invalid SIG(0) record followed by a premature transport close. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | All signals point to a genuine but availability-only remote DoS. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | Full exploit scenario with step-by-step reproduction available after sign-in. |
| Remediation | The primary fix is to upgrade to a BIND 9 release containing the correction: 9.20.29 for the 9.20 stable branch (https://downloads.isc.org/isc/bind9/9.20.29) or 9.21.26 for the 9.21 development branch (https://downloads.isc.org/isc/bind9/9.21.26), following the vendor advisory at https://kb.isc.org/docs/cve-2026-77692 for branch-specific and subscription (-S1) guidance, since no -S1 fix artifact is listed in the supplied references. … Detailed patch versions, workarounds, and compensating controls in full report. |
Recommended ActionAI
Within 24 hours, inventory every BIND 9 named instance and confirm whether the DoH transport is enabled and whether SIG(0)-signed messages are processed; for any internet-facing or partner-reachable resolver where DoH is not a business requirement, disable the DoH listener immediately to eliminate the reachable attack surface, and apply vendor patches on the highest-exposure systems first. …
Sign in for detailed remediation steps and compensating controls.
Threat intelligence, references, and detailed analysis are available after sign-in.
BIND resolver servers performing DNSSEC validation can be forced into excessive CPU consumption when encountering a mali
Memory exhaustion in BIND 9 resolver allows unauthenticated remote attackers to cause denial of service by querying spec
Memory corruption in ISC BIND 9's DNS-over-HTTPS (DoH) implementation lets remote attackers trigger a use-after-free (CW
DNSSEC validation bypass in ISC BIND 9 resolvers (9.11.0 through 9.21.23 and S-editions) allows an attacker controlling
Denial of service in ISC BIND 9 lets a remote unauthenticated attacker exhaust resolver memory by flooding a DNSSEC-vali
Remote denial of service in ISC BIND 9 lets an attacker crash a validating resolver via a maliciously crafted DNSSEC pro
Denial of service in ISC BIND 9 resolvers (9.20.0-9.20.24, 9.21.0-9.21.23, and 9.20.9-S1-9.20.24-S1) lets remote unauthe
Cache poisoning in ISC BIND 9 recursive resolvers allows an attacker who controls an authoritative zone to inject forged
RPZ policy bypass and remote denial-of-service in ISC BIND 9 resolvers lets unauthenticated attackers defeat Response Po
Remote denial of service in ISC BIND 9 lets an off-path attacker crash a recursive resolver by controlling the timing an
Denial of service in ISC BIND 9 DNS servers configured with TKEY GSS-API authentication allows remote unauthenticated at
Remote denial of service in ISC BIND 9 named allows unauthenticated attackers to trigger assertion failures and crash th
Same weakness CWE-476 – NULL Pointer Dereference
View allSame technique Denial Of Service
View allShare
External POC / Exploit Code
Leaving vuln.today