CVE-2025-62408: c-ares is an asynchronous resolver library

Routine

MEDIUM 5.9REMOTEUPGRADE

CVE-2025-62408 is a medium-severity flaw (CVSS 5.9) affecting c-ares. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

c-ares is an asynchronous resolver library. Versions 1.32.3 through 1.34.5 terminate a query after maximum attempts when using read_answer() and process_answer(), which can cause a Denial of Service. This issue is fixed in version 1.34.6.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.9 (Medium)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 63%)
CISA exploited list	No
Weakness	CWE-416
Published	2025-12-08
Last modified	2026-10-14

Publisher (CNA): GitHub, Inc. · Vendor: c-ares

Last updated 2026-10-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2025-12-08 22:15 UTCPublished CVE record published
2026-10-14 22:10 UTCUpdated Record last modified

c-ares c-ares UPGRADE

Affected: >= 1.32.3 and < 1.34.6

Fixed in: 1.34.6

Safe to downgrade to: a release before 1.32.3

1. Check installed version

apt-cache policy c-ares || rpm -q c-ares || c-ares --version

2. UPGRADE to 1.34.6 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade c-ares

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade c-ares

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 1.32.3 (Debian / Ubuntu)

apt-cache madison c-ares sudo apt install c-ares=<VERSION_BEFORE_1.32.3> sudo apt-mark hold c-ares

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list c-ares sudo dnf downgrade c-ares-<VERSION_BEFORE_1.32.3> sudo dnf versionlock add c-ares

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2025-62408?

c-ares: upgrade to 1.34.6. Exact commands for each OS are on this page.

Is CVE-2025-62408 being exploited?

CVE-2025-62408 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2025-62408 affect?

CVE-2025-62408 affects c-ares. Severity is medium (CVSS 5.9). c-ares is an asynchronous resolver library. Versions 1.32.3 through 1.34.5 terminate a query after maximum attempts when using read_answer() and process_answer(), which can cause a Denial of Service. This issue is fixed in version 1.34.6.

How urgent is CVE-2025-62408?

Priority 35/100. Remotely exploitable, no login, no user action

References

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