CVE-2025-40777

CWE-617 — Reachable Assertion9 documents8 sources
Severity
7.5HIGH
EPSS
0.0%
top 92.78%
CISA KEV
Not in KEV
Exploit
No known exploits
Affected products
1
ISC Bind 9
Timeline
PublishedJul 16

Description

If a `named` caching resolver is configured with `serve-stale-enable` `yes`, and with `stale-answer-client-timeout` set to `0` (the only allowable value other than `disabled`), and if the resolver, in the process of resolving a query, encounters a CNAME chain involving a specific combination of cached or authoritative records, the daemon will abort with an assertion failure. This issue affects BIND 9 versions 9.20.0 through 9.20.10, 9.21.0 through 9.21.9, and 9.20.9-S1 through 9.20.10-S1.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HExploitability: 3.9 | Impact: 3.6

Affected Packages3 packages

▶Alpinebind< 9.20.11-r0+1
▶Debianbind9< 1:9.20.11-1+1
▶CVEListV5isc/bind_99.20.0 — 9.20.10+2

🔴Vulnerability Details

4
OSV
CVE-2025-40777: If a `named` caching resolver is configured with `serve-stale-enable` `yes`, and with `stale-answer-client-timeout` set to `0` (the only allowable val↗2025-07-16
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GHSA
GHSA-4x4c-8qp9-8ggh: If a `named` caching resolver is configured with `serve-stale-enable` `yes`, and with `stale-answer-client-timeout` set to `0` (the only allowable val↗2025-07-16
▶
OSV
CVE-2025-40777: If a `named` caching resolver is configured with `serve-stale-enable` `yes`, and with `stale-answer-client-timeout` set to `0` (the only allowable val↗2025-07-16
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CVEList
A possible assertion failure when 'stale-answer-client-timeout' is set to '0'↗2025-07-16
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📋Vendor Advisories

4
Ubuntu
Bind vulnerability↗2025-07-16
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Red Hat
bind: bind assertion failure↗2025-07-16
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Microsoft
A possible assertion failure when 'stale-answer-client-timeout' is set to '0'↗2025-07-08
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Debian
CVE-2025-40777: bind9 - If a `named` caching resolver is configured with `serve-stale-enable` `yes`, and...↗2025
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