SB2025071772 - Ubuntu update for bind9
Published: July 17, 2025
Security Bulletin ID
SB2025071772
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Denial of service
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Reachable assertion (CVE-ID: CVE-2025-40777)
CWE-ID: CWE-617 - Reachable Assertion
CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green
The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.
The vulnerability exists due to a reachable assertion when named caching resolver is configured with "serve-stale-enable=yes" and "stale-answer-client-timeout=0". A remote attacker can supply a specially crafted CNAME chain in DNS response and perform a denial of service attack against the resolver.
Remediation
Install update from vendor's website.