CVE catalog

CVE-2023-31147

c-ares affected and fixed versions

c-ares is an asynchronous resolver library. When /dev/urandom or RtlGenRandom() are unavailable, c-ares uses rand() to generate random numbers used for DNS query ids. This is not a CSPRNG, and it is also not seeded by srand() so will generate predictable output. Input from the random number generator is fed into a non-compilant RC4 implementation and may not be as strong as the original RC4 implementation. No attempt is made to look for modern OS-provided CSPRNGs like arc4random() that is widely available. This issue has been fixed in version 1.19.1.

Severity: Medium · CVSS 5.9CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Published: May 22, 2023, 12:00:00 AM UTC
Source: [NVD] · [CVE record]
EPSS: 0.90% · Oct 27, 2026

Projects and upstream resources

[c-ares][Source-reported homepage]

Reported versions and fixes

Each observation applies to its named package, distribution, and release. Distribution backports can fix a vulnerability while retaining an older upstream version number.

Distribution / release	Package	Version	Status	Source
Debiantrixie-security	c-ares	`1.34.5-1+deb13u1`	Fixed	[CVE-2023-31147]
Debiantrixie	c-ares	`1.19.1-2`	FixedDistribution-reported fixed boundary	[CVE-2023-31147]
Debiantrixie	c-ares	`1.34.5-1+deb13u1`	Fixed	[CVE-2023-31147]
Debiansid	c-ares	`1.19.1-2`	FixedDistribution-reported fixed boundary	[CVE-2023-31147]
Debiansid	c-ares	`1.34.9-1`	Fixed	[CVE-2023-31147]
Debianforky	c-ares	`1.19.1-2`	FixedDistribution-reported fixed boundary	[CVE-2023-31147]
Debianforky	c-ares	`1.34.8-1`	Fixed	[CVE-2023-31147]

Showing 7 fix observations. All 10 observations, including unknown and conflicting reports, are available below.

Provider details and historical evidence

Distribution / release	Package	Version	Status	Source
UnknownRelease not reported	c-ares	Not reported	UnknownSource applicability is not established	Provider not reported
Debianbookworm	c-ares	Not reported	AffectedDistribution reports no fix	[CVE-2023-31147]
Debianbookworm	c-ares	`1.18.1-3`	Affected	[CVE-2023-31147]
Debianforky	c-ares	`1.19.1-2`	FixedDistribution-reported fixed boundary	[CVE-2023-31147]
Debianforky	c-ares	`1.34.8-1`	Fixed	[CVE-2023-31147]
Debiansid	c-ares	`1.19.1-2`	FixedDistribution-reported fixed boundary	[CVE-2023-31147]
Debiansid	c-ares	`1.34.9-1`	Fixed	[CVE-2023-31147]
Debiantrixie	c-ares	`1.19.1-2`	FixedDistribution-reported fixed boundary	[CVE-2023-31147]
Debiantrixie	c-ares	`1.34.5-1+deb13u1`	Fixed	[CVE-2023-31147]
Debiantrixie-security	c-ares	`1.34.5-1+deb13u1`	Fixed	[CVE-2023-31147]

Original provider fields

{
  "package_releases": [
    {
      "name": "c-ares",
      "status": "fixed",
      "release": "sid",
      "version": "1.34.9-1"
    },
    {
      "name": "c-ares",
      "status": "fixed",
      "release": "forky",
      "version": "1.34.8-1"
    },
    {
      "name": "c-ares",
      "status": "fixed",
      "release": "trixie",
      "version": "1.34.5-1+deb13u1"
    },
    {
      "name": "c-ares",
      "status": "fixed",
      "release": "trixie-security",
      "version": "1.34.5-1+deb13u1"
    },
    {
      "name": "c-ares",
      "status": "vulnerable",
      "release": "bookworm",
      "version": "1.18.1-3"
    }
  ],
  "fixed_versions": [
    {
      "bug": null,
      "name": "c-ares",
      "type": "source",
      "origin": null,
      "release": "sid",
      "urgency": "unimportant",
      "fixed_version": "1.19.1-2"
    },
    {
      "bug": null,
      "name": "c-ares",
      "type": "source",
      "origin": null,
      "release": "forky",
      "urgency": "unimportant",
      "fixed_version": "1.19.1-2"
    },
    {
      "bug": null,
      "name": "c-ares",
      "type": "source",
      "origin": null,
      "release": "trixie",
      "urgency": "unimportant",
      "fixed_version": "1.19.1-2"
    },
    {
      "bug": null,
      "name": "c-ares",
      "type": "source",
      "origin": null,
      "release": "bookworm",
      "urgency": "unimportant",
      "fixed_version": ""
    }
  ],
  "distribution_packages": [
    {
      "name": "c-ares",
      "fixed_version": "not yet fixed",
      "applicability_unknown": true
    }
  ]
}

OpenFactory catalog packages

Matching against OpenFactory catalog package versions is in progress.

[Debian 12 (Bookworm)]

[libc-ares2]Unknown
Source package: [c-ares]
Details (2)
- 1.18.1-3 · amd64 · bookworm
  Affected
  dsa · c-ares · debian · bookworm; dsa · c-ares · debian · 12
- 1.18.1-3 · arm64 · bookworm
  Affected
  dsa · c-ares · debian · bookworm; dsa · c-ares · debian · 12
[libc-ares-dev]Unknown
Source package: [c-ares]
Details (2)
- 1.18.1-3 · amd64 · bookworm
  Affected
  dsa · c-ares · debian · bookworm; dsa · c-ares · debian · 12
- 1.18.1-3 · arm64 · bookworm
  Affected
  dsa · c-ares · debian · bookworm; dsa · c-ares · debian · 12

[Debian 13 (Trixie)]

[libc-ares2]Unknown
Source package: [c-ares]
Details (4)
- 1.34.5-1+deb13u1 · all · trixie
  Fixed · Fixed: 1.19.1-2
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · all · trixie
  Fixed · Fixed: 1.19.1-2
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · all · trixie-security
  Fixed · Fixed: 1.19.1-2
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · all · trixie-security
  Fixed · Fixed: 1.19.1-2
  dsa · c-ares · debian · 13
[libcares2]Unknown
Source package: [c-ares]
Details (4)
- 1.34.5-1+deb13u1 · amd64 · trixie
  Fixed · Fixed: 1.19.1-2
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · arm64 · trixie
  Fixed · Fixed: 1.19.1-2
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 1.19.1-2
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · arm64 · trixie-security
  Fixed · Fixed: 1.19.1-2
  dsa · c-ares · debian · 13
[libc-ares-dev]Unknown
Source package: [c-ares]
Details (4)
- 1.34.5-1+deb13u1 · amd64 · trixie
  Fixed · Fixed: 1.19.1-2
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · arm64 · trixie
  Fixed · Fixed: 1.19.1-2
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 1.19.1-2
  dsa · c-ares · debian · 13
- 1.34.5-1+deb13u1 · arm64 · trixie-security
  Fixed · Fixed: 1.19.1-2
  dsa · c-ares · debian · 13

Observed: Oct 28, 2026, 5:46:12 PM UTC

References

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