CVE-2026-41401: libyang · Use After Free
Affects libyangSource CVE Database V5
Public exploit available · CVSS 6.9 Medium : upgrade to 5.4.3 as a priority.
Data as of 29 Oct 2026, 21:45 UTC
Thin evidence
One scorer or none| CNA (VulnCheck) | CVSS 4.0 | 6.9 |
|---|---|---|
| CNA (VulnCheck) | CVSS 3.1 | 6.5 |
- CISA SSVC
- Exploitation
- Proof of concept is public or traded
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-05-26.
- Patch
- Available – fixed in 5.4.3
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NExploitation evidence
t = 0 is the CVE’s publication on cve.org
Disclosed: evidence found.
CVE published 26 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: evidence found.
CISA SSVC: proof of concept public
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
Timeline
CVE ID reserved
by VulnCheck
, 36 days before disclosure
CVE published
on cve.org
, t = 0
CISA SSVC assessment
proof of concept public
, 4 hours after disclosure
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CISA SSVC, the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade libyang to 5.4.3.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| libyanglibyang | Affected
| Fixed in
|
AI-suggested
Upgrade libyang to version 5.4.3 or later, where this use-after-free vulnerability is fixed. No other mitigations are indicated or required according to the available data.
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.
References
- github.com/CESNET/libyang/security/advisories/GHSA-9f49-8x56-jmjc (opens in a new tab)
- github.com/CESNET/libyang/commit/6b5ed47ee674fbe86b31bbebc4ff26889aeff38c (opens in a new tab)
- red.anthropic.com/2026/cvd/findings/ANT-2026-TZQ1KH7E (opens in a new tab)
- vulncheck.com/advisories/libyang-heap-use-after-free-write-in-xml-metadata-parsing (opens in a new tab)