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.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (0.52%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
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.
- CVSS 4.0
- 7.1 HIGHCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.52% probability · 43th percentile
- CISA KEV
- Not listed
- Weakness
- CWE-416
- Source
- disclosure@vulncheck.com
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
Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.