CVE-2023-5156: A flaw was found in the GNU C Library

Q: How do I fix CVE-2023-5156?

glibc: upgrade to 2.39; enterprise linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2023-5156 being exploited?

CVE-2023-5156 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2023-5156 affect?

CVE-2023-5156 affects glibc, enterprise linux. Severity is high (CVSS 7.5). A flaw was found in the GNU C Library. A recent fix for CVE-2023-4806 introduced the potential for a memory leak, which may result in an application crash.

Q: How urgent is CVE-2023-5156?

Priority 55/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

This month

HIGH 7.5REMOTEWATCHLISTUPGRADEMITIGATE

CVE-2023-5156 is a high-severity flaw (CVSS 7.5) affecting glibc, enterprise linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A flaw was found in the GNU C Library. A recent fix for CVE-2023-4806 introduced the potential for a memory leak, which may result in an application crash.

Why this priority

High severity
Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.6% (top 24%)
CISA exploited list	No
Weakness	CWE-401
Published	2023-09-25
Last modified	2026-10-14

Publisher (CNA): Red Hat, Inc. · Vendor: gnu · redhat

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

Am I affected?

Timeline

2023-09-25 16:15 UTCPublished CVE record published
2026-10-14 22:17 UTCUpdated Record last modified

gnu glibc UPGRADE

Affected: >= 2.34 and < 2.39

Fixed in: 2.39

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy glibc || rpm -q glibc || glibc --version

2. UPGRADE to 2.39 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade glibc

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade glibc

Note

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

redhat enterprise linux MITIGATE

Affected: 8.0 · 9.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2023-5156?

glibc: upgrade to 2.39; enterprise linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2023-5156 being exploited?

CVE-2023-5156 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-2023-5156 affect?

CVE-2023-5156 affects glibc, enterprise linux. Severity is high (CVSS 7.5). A flaw was found in the GNU C Library. A recent fix for CVE-2023-4806 introduced the potential for a memory leak, which may result in an application crash.

How urgent is CVE-2023-5156?

Priority 55/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

glibc vulnerabilities

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References

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