Reachable assertion in ISC BIND9
Priority LOW 39CWE-617Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- Denial of service
- Confidentiality · integrity · availability
- None · None · High
- Fix status
- No fix listed
Attack profile from CVSS 3.1 · CNA. Fix status from CNA. Impact type from CWE-617.
Summary
In BIND 9.16.19, 9.17.16. Also, version 9.16.19-S1 of BIND Supported Preview Edition When a vulnerable version of named receives a query under the circumstances described above, the named process will terminate due to a failed assertion check. The vulnerability affects only BIND 9 releases 9.16.19, 9.17.16, and release 9.16.19-S1 of the BIND Supported Preview Edition.
Why it matters now
EPSS 0.03658 89th percentileScored 2026-11-08
Public exploit Yes 1 exploit referenceTagged by NVD
Fix No fix listed No fixed version in the sources yet
SSVC decision points
Not available: CISA has not published SSVC decision points for this record.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| ISC | BIND9 | Stable Branch 9.16.19; Development Branch 9.17.16; Supported Preview Edition 9.16.19-S1 | — | No fix listed | CNA |
- BIND9 VendorISC Affected Stable Branch 9.16.19; Development Branch 9.17.16; Supported Preview Edition 9.16.19-S1 Fixed in — No fix listed CNA
CPE configurations NVD · 4
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:isc:bind:9.16.19:*:*:*:-:*:*:* | 9.16.19 | Vulnerable | ISC |
| cpe:2.3:a:isc:bind:9.17.16:*:*:*:-:*:*:* | 9.17.16 | Vulnerable | ISC |
| cpe:2.3:a:isc:bind:9.17.16:s1:*:*:supported_preview:*:*:* | 9.17.16 s1 | Vulnerable | ISC |
| cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* | 34 | Vulnerable | Fedoraproject |
- cpe:2.3:a:isc:bind:9.16.19:*:*:*:-:*:*:* Versions 9.16.19 Vulnerable ·ISC
- cpe:2.3:a:isc:bind:9.17.16:*:*:*:-:*:*:* Versions 9.17.16 Vulnerable ·ISC
- cpe:2.3:a:isc:bind:9.17.16:s1:*:*:supported_preview:*:*:* Versions 9.17.16 s1 Vulnerable ·ISC
- cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:* Versions 34 Vulnerable ·Fedoraproject
Remediation
No fixed version listed by the sources yet.
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
Not affected: 5 products
- Red Hat Enterprise Linux 6
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
- Red Hat Virtualization 4
Timeline
- 2026-10-02 Threatist record created from CVE-2021-25218
- 2026-10-03 Alias added: GHSA-cc8x-chx9-c63q
References
Patch 2
More ISC Bind vulnerabilities
- TI-2015-04610 Assertion failure in ISC BIND named via TKEY queries KEVCVSS 3.1HIGH 7.5
- TI-2023-27571 Certain DNSSEC aspects of the DNS protocol (in RFC 4033, 4034, 4035, 6840, and related… CVSS 3.1HIGH 7.5
- TI-2021-07476 A second vulnerability in BIND's GSSAPI security policy negotiation can be targeted by a buffer overflow attack CVSS 3.1CRITICAL 9.8
- TI-2023-27773 The Closest Encloser Proof aspect of the DNS protocol (in RFC 5155 when RFC 9276 guidance… CVSS 3.1HIGH 7.5
- TI-2020-06910 A logic error in code which checks TSIG validity can be used to trigger an assertion failure in tsig.c CVSS 3.1HIGH 7.5
- TI-2016-02320 buffer.c in named in ISC BIND 9 before 9.9.9-P3, 9.10.x before 9.10.4-P3, and 9.11.x… CVSS 3.0HIGH 7.5
Sources
- CVE-2021-25218 · CVE Program
- CVE-2021-25218 · NVD
- FIRST EPSS
- GHSA-cc8x-chx9-c63q · GitHub Advisory Database · CC BY 4.0
- CVE-2021-25218 · Red Hat security data · CC BY 4.0
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