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

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HIGH 7.5REMOTEUPGRADE

CVE-2023-26917 is a high-severity flaw (CVSS 7.5) affecting libyang. 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 lysp_stmt_validate_value at lys_parse_mem.c.

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

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	0.9% (top 41%)
CISA exploited list	No
Weakness	CWE-476
Published	2023-04-11
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: cesnet

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

Am I affected?

Timeline

2023-04-11 12:15 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.

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-2023-26917?

libyang: upgrade to newer than 2.1.30. Exact commands for each OS are on this page.

Is CVE-2023-26917 being exploited?

CVE-2023-26917 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-2023-26917 affect?

CVE-2023-26917 affects libyang. Severity is high (CVSS 7.5). libyang from v2.0.164 to v2.1.30 was discovered to contain a NULL pointer dereference via the function lysp_stmt_validate_value at lys_parse_mem.c.

How urgent is CVE-2023-26917?

Priority 51/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2023-26916 MEDIUM 5.3 UPGRADE MITIGATE libyang from v2.0.164 to v2.1.30 was discovered to contain a NULL pointer dereference via the function lys_par

References

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