# CVE-2026-63729: TeX Live SyncTeX Parser Heap Use-After-Free via Malformed SyncTeX File

> Attackers can execute arbitrary code or crash applications by providing a malformed SyncTeX file to TeX Live or dependent viewers like Evince.

- **Severity:** Medium 6.8 (`CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:L/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 21 Jul 2026
- **Updated:** 24 Sep 2026
- **Also known as:** DEBIAN-CVE-2026-63729, ECHO-29b4-3924-6adf, GHSA-jf22-92mg-7xxh, OESA-2026-3192, SUSE-SU-2026:3512-1, SUSE-SU-2026:3924-1, UBUNTU-CVE-2026-63729, openSUSE-SU-2026:11412-1

## What is CVE-2026-63729?

CVE-2026-63729 is a medium-severity use after free vulnerability in TeX Live, published on 21 Jul 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

The SyncTeX parser (synctex_parser.c) shipped with TeX Live and embedded by downstream consumers such as GNOME Evince contains a heap use-after-free vulnerability that allows attackers to crash applications or potentially execute arbitrary code by supplying a malformed .synctex or .synctex.gz file. A malformed SyncTeX file can construct a ref node with a NULL parent pointer, causing the replacement routine to fail to detach the node from its sibling chain, which triggers recursive freeing of live tree nodes and leaves dangling pointers that are later accessed by the parser during document load.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2026-63729?


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `evince` | SUSE:Linux Enterprise Module for Desktop Applications 15 SP7 | All versions | 45.0-150600.3.6.1 |
| `texlive` | SUSE:Linux Enterprise Server LTSS Extended Security 12 SP5 | All versions | 2013.20130620-22.14.1 |
| `evince` | openSUSE:Tumbleweed | All versions | 48.4-2.1 |

## How do I fix CVE-2026-63729?

Apply the vendor's patch.

## Is CVE-2026-63729 being exploited?

There is no known exploitation of CVE-2026-63729 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-63729 and fix it if it is affected.

What it is: CVE-2026-63729 is a medium-severity use after free vulnerability in TeX Live, published on 21 Jul 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-63729 in the wild and no public exploit code.

Affected product: TeX Live. 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-2026-63729/ (Markdown: https://insights.sbomify.com/CVE-2026-63729/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-63729
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-63729
- OSV: https://osv.dev/vulnerability/CVE-2026-63729

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-63729/
Summaries are generated and may contain mistakes; the official description above is the record.