CVE catalog

CVE-2025-31498

c-ares: CVE-2025-31498

Severity: High · CVSS 7CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H
Published: Apr 8, 2025, 1:53:11 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.59% · Oct 27, 2026

c-ares is an asynchronous resolver library. From 1.32.3 through 1.34.4, there is a use-after-free in read_answers() when process_answer() may re-enqueue a query either due to a DNS Cookie Failure or when the upstream server does not properly support EDNS, or possibly on TCP queries if the remote closed the connection immediately after a response. If there was an issue trying to put that new transaction on the wire, it would close the connection handle, but read_answers() was still expecting the connection handle to be available to possibly dequeue other responses. In theory a remote attacker might be able to trigger this by flooding the target with ICMP UNREACHABLE packets if they also control the upstream nameserver and can return a result with one of those conditions, this has been untested. Otherwise only a local attacker might be able to change system behavior to make send()/write() return a failure condition. This vulnerability is fixed in 1.34.5.

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	c-ares	sid	`1.34.9-1`	fixed
Debian	c-ares	forky	`1.34.8-1`	fixed
Debian	c-ares	trixie	`1.34.5-1+deb13u1`	fixed
Debian	c-ares	trixie-security	`1.34.5-1+deb13u1`	fixed
Debian	c-ares	bookworm	`1.18.1-3`	not affected
Suse	c-ares	linux micro 6.1	`1.34.8-slfo.1.1_1.1`	fixed
Suse	c-ares	linux micro 6.0	`1.34.8-1.1`	fixed
Alpine	c-ares	3.21	`1.34.5-r0`	fixed
Alpine	c-ares	3.22	`1.34.5-r0`	fixed
Alpine	c-ares	3.23	`1.34.5-r0`	fixed
Alpine	c-ares	3.24	`1.34.5-r0`	fixed
Opensuse	c-ares	tumbleweed	`1.34.5-1.1`	fixed
Ubuntu	c-ares	25.04	`1.33.0-1`	vulnerable
Ubuntu	c-ares	25.04	`1.34.2-1`	vulnerable
Ubuntu	c-ares	25.04	`1.34.3-1`	vulnerable
Ubuntu	c-ares	25.04	`1.34.4-1`	vulnerable
Ubuntu	c-ares	25.04	`1.34.4-2.1`	vulnerable
Ubuntu	c-ares	25.04	`1.34.4-2.1ubuntu0.1`	fixed

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	c-ares	source	sid	`1.34.5-1`	not yet assigned	Not reported	Not reported
Debian	c-ares	source	forky	`1.34.5-1`	not yet assigned	Not reported	Not reported
Debian	c-ares	source	trixie	`1.34.5-1`	not yet assigned	Not reported	Not reported
Debian	c-ares	source	bookworm	`Not affected`	unimportant	Not reported	Not reported
Suse	c-ares	rpm	linux micro 6.1	`1.34.8-slfo.1.1_1.1`	Not reported	SUSE-SU-2026:23414-1	Not reported
Suse	c-ares	rpm	linux micro 6.0	`1.34.8-1.1`	Not reported	SUSE-SU-2026:23364-1	Not reported
Alpine	c-ares	apk	3.21	`1.34.5-r0`	Not reported	ALPINE-CVE-2025-31498	Not reported
Alpine	c-ares	apk	3.22	`1.34.5-r0`	Not reported	ALPINE-CVE-2025-31498	Not reported
Alpine	c-ares	apk	3.23	`1.34.5-r0`	Not reported	ALPINE-CVE-2025-31498	Not reported
Alpine	c-ares	apk	3.24	`1.34.5-r0`	Not reported	ALPINE-CVE-2025-31498	Not reported
Opensuse	c-ares	rpm	tumbleweed	`1.34.5-1.1`	Not reported	OPENSUSE-SU-2025:14977-1	Not reported
Ubuntu	c-ares	deb	25.04	`1.34.4-2.1ubuntu0.1`	Not reported	USN-7477-1	Not reported

OpenFactory catalog packages

[openSUSE Tumbleweed]

[c-ares-devel]Unknown
Source package: [c-ares]
Details (1)
- 1.34.8-1.1 · x86_64 · tumbleweed
  Unknown · Fixed: 1.34.5-1.1
  Version impact unknown
  dsa · c-ares · opensuse · tumbleweed
[c-ares-utils]Unknown
Source package: [c-ares]
Details (1)
- 1.34.8-1.1 · x86_64 · tumbleweed
  Unknown · Fixed: 1.34.5-1.1
  Version impact unknown
  dsa · c-ares · opensuse · tumbleweed
[libcares2]Unknown
Source package: [c-ares]
Details (1)
- 1.34.8-1.1 · x86_64 · tumbleweed
  Unknown · Fixed: 1.34.5-1.1
  Version impact unknown
  dsa · c-ares · opensuse · tumbleweed
[libcares2-32bit]Unknown
Source package: [c-ares]
Details (1)
- 1.34.8-1.1 · x86_64 · tumbleweed
  Unknown · Fixed: 1.34.5-1.1
  Version impact unknown
  dsa · c-ares · opensuse · tumbleweed

[Debian 12 (Bookworm)]

[libc-ares2]Not affected
Source package: [c-ares]
Details (2)
- 1.18.1-3 · amd64 · bookworm
  Not affected
  dsa · c-ares · debian · bookworm
- 1.18.1-3 · arm64 · bookworm
  Not affected
  dsa · c-ares · debian · bookworm
[libc-ares-dev]Not affected
Source package: [c-ares]
Details (2)
- 1.18.1-3 · amd64 · bookworm
  Not affected
  dsa · c-ares · debian · bookworm
- 1.18.1-3 · arm64 · bookworm
  Not affected
  dsa · c-ares · debian · bookworm

[Debian 13 (Trixie)]

[libc-ares2]Fixed
Source package: [c-ares]
Details (4)
- 1.34.5-1+deb13u1 · all · trixie
  Fixed · Fixed: 1.34.5-1
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · all · trixie
  Fixed · Fixed: 1.34.5-1
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · all · trixie-security
  Fixed · Fixed: 1.34.5-1
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · all · trixie-security
  Fixed · Fixed: 1.34.5-1
  dsa · c-ares · debian · 13
[libcares2]Fixed
Source package: [c-ares]
Details (4)
- 1.34.5-1+deb13u1 · amd64 · trixie
  Fixed · Fixed: 1.34.5-1
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · arm64 · trixie
  Fixed · Fixed: 1.34.5-1
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 1.34.5-1
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · arm64 · trixie-security
  Fixed · Fixed: 1.34.5-1
  dsa · c-ares · debian · 13
[libc-ares-dev]Fixed
Source package: [c-ares]
Details (4)
- 1.34.5-1+deb13u1 · amd64 · trixie
  Fixed · Fixed: 1.34.5-1
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · arm64 · trixie
  Fixed · Fixed: 1.34.5-1
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 1.34.5-1
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · arm64 · trixie-security
  Fixed · Fixed: 1.34.5-1
  dsa · c-ares · debian · 13

Observed: Oct 27, 2026, 2:53:08 PM UTC

References

[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]