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

> Attackers can trigger a heap use-after-free write in libyang via crafted XML, potentially leading to code execution or crashes.

- **Severity:** Medium 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 26 May 2026
- **Updated:** 29 Oct 2026
- **Also known as:** AZL-87354, DEBIAN-CVE-2026-41401, GHSA-9f49-8x56-jmjc, GHSA-v7jp-vmx6-5429, MGASA-2026-0302, UBUNTU-CVE-2026-41401, USN-8485-1, openSUSE-SU-2026:10868-1

## What is CVE-2026-41401?

CVE-2026-41401 is a medium-severity use after free vulnerability in libyang, published on 26 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official 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.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-41401?


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `libyang` | openSUSE:Tumbleweed | All versions | 3.13.6-2.1 |

## How do I fix CVE-2026-41401?

Upgrade to a fixed version.

## Is CVE-2026-41401 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41401 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-41401 and fix it if it is affected.

What it is: CVE-2026-41401 is a medium-severity use after free vulnerability in libyang, published on 26 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-41401 exists.

Affected product: libyang. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-41401/ (Markdown: https://insights.sbomify.com/CVE-2026-41401/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-41401
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-41401
- OSV: https://osv.dev/vulnerability/CVE-2026-41401

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-41401/
Summaries are generated and may contain mistakes; the official description above is the record.