Use After Free in Libyang
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.
Vulnerability class: Use-After-Free
Published · last modified .
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.006 (49.0th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 49th percentile — 49.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.005 · newest: 0.006 · change: +0.001
Affected products
- Libyang — versions 0, 5.4.3
Weakness classification (CWE)
References
- github.com/CESNET/libyang/security/advisories/GHSA-9f49-8x56-jmjc (vendor-advisory)
- github.com/CESNET/libyang/commit/6b5ed47ee674fbe86b31bbebc4ff26889aeff38c (patch)
- red.anthropic.com/2026/cvd/findings/ANT-2026-TZQ1KH7E (third-party-advisory)
- www.vulncheck.com/advisories/libyang-heap-use-after-free-write-in-xml-metadata-… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-41401?
- CVE-2026-41401 is a medium-severity vulnerability in Libyang, classified under Use After Free. CVSS score: 6.5/10. Published 2026-05-26.
- How severe is CVE-2026-41401?
- Medium severity. CVSS v3 base score is 6.5 out of 10.