CVE-2026-41401: Use-After-Free (CVSS 6.5)

Description

libyang before 5.2.6 contains a heap use-after-free write vulnerability in lyd_parser_set_data_flags that incorrectly updates metadata list pointers when freeing non-head default metadata entries. Attackers can trigger this vulnerability by submitting crafted YANG XML documents with specific metadata attributes to applications parsing untrusted XML data, causing process crashes or potential code execution.

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CVSS v3.1 Score

6.5

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

EPSS — Exploit Prediction

0.0052

Probability of exploitation

0.40%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-416 Use After Free

References

Other References

https://github.com/CESNET/libyang/commit/6b5ed47ee674fbe86b31bbebc4ff26889aeff38c https://github.com/CESNET/libyang/security/advisories/GHSA-9f49-8x56-jmjc https://red.anthropic.com/2026/cvd/findings/ANT-2026-TZQ1KH7E https://www.vulncheck.com/advisories/libyang-heap-use-after-free-write-in-xml-metadata-parsing https://github.com/CESNET/libyang/security/advisories/GHSA-9f49-8x56-jmjc https://red.anthropic.com/2026/cvd/findings/ANT-2026-TZQ1KH7E

Frequently Asked Questions

What is CVE-2026-41401? +

libyang before 5.2.6 contains a heap use-after-free write vulnerability in lyd_parser_set_data_flags that incorrectly updates metadata list pointers when freeing non-head default metadata entries. Attackers can trigger this vulnerability by submitting crafted YANG XML documents with specific metadata attributes to applications parsing untrusted XML data, causing process crashes or potential code execution. It has a CVSS v3.1 base score of 6.5 (MEDIUM).

How severe is CVE-2026-41401? +

CVE-2026-41401 has a CVSS v3.1 score of 6.5 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0052, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-41401? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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