What’s Vulnerable › Vulnerabilities

CVE-2026-41401: libyang - Heap Use-After-Free Write in XML Metadata Parsing

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.7% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-05-26 · updated 2026-10-29
• Weakness: CWE-416

Description

libyang before 5.4.3 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.

Affected products

• libyang: before 5.4.3 — fixed in 5.4.3

How to fix

Upgrade to a fixed version: libyang 5.4.3. Check the vendor advisory for mitigations.

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

Get alerted when CVE-2026-41401 or the next vulnerability affects your stack