CVE-2023-26916: libyang from v2.0.164 to v2.1.30 was discovered to contain a NULL pointer dereference via the function lys_par

Routine

MEDIUM 5.3REMOTEUPGRADEMITIGATE

CVE-2023-26916 is a medium-severity flaw (CVSS 5.3) affecting libyang, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

libyang from v2.0.164 to v2.1.30 was discovered to contain a NULL pointer dereference via the function lys_parse_mem at lys_parse_mem.c.

Why this priority

Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.0% (top 38%)
CISA exploited list	No
Weakness	CWE-476
Published	2023-04-03
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: cesnet · fedoraproject

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2023-04-03 22:15 UTCPublished CVE record published
2026-06-17 05:43 UTCUpdated Record last modified

cesnet libyang UPGRADE

Affected: >= 2.0.164 and <= 2.1.30

Fixed in: newer than 2.1.30

Safe to downgrade to: a release before 2.0.164

1. Check installed version

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

2. UPGRADE to newer than 2.1.30 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade libyang

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 2.0.164 (Debian / Ubuntu)

apt-cache madison libyang sudo apt install libyang=<VERSION_BEFORE_2.0.164> sudo apt-mark hold libyang

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

dnf --showduplicates list libyang sudo dnf downgrade libyang-<VERSION_BEFORE_2.0.164> sudo dnf versionlock add libyang

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.

fedoraproject fedora MITIGATE

Affected: 36 · 37

Fixed in: no fixed release known

Safe to downgrade to: a release before 36

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-2023-26916?

libyang: upgrade to newer than 2.1.30; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2023-26916 being exploited?

CVE-2023-26916 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-2023-26916 affect?

CVE-2023-26916 affects libyang, fedora. Severity is medium (CVSS 5.3). libyang from v2.0.164 to v2.1.30 was discovered to contain a NULL pointer dereference via the function lys_parse_mem at lys_parse_mem.c.

How urgent is CVE-2023-26916?

Priority 39/100. Remotely exploitable, no login, no user action

Related CVEs

CVE-2023-26917 HIGH 7.5 UPGRADE libyang from v2.0.164 to v2.1.30 was discovered to contain a NULL pointer dereference via the function lysp_st

References

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