# CVE-2026-107734: SumatraPDF: SyncTeX Argument Injection in Inverse Search Enables Arbitrary Command Execution via External Editors

> Attackers can execute arbitrary commands via crafted SyncTeX files in SumatraPDF if an external editor is configured and inverse search is used.

- **Severity:** High 7.1 (`CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/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:** No
- **Published:** 8 Oct 2026
- **Updated:** 9 Oct 2026
- **Also known as:** GHSA-jf4v-rw66-j4w2

## What is CVE-2026-107734?

CVE-2026-107734 is a high-severity command injection vulnerability in sumatrapdfreader sumatrapdf, published on 8 Oct 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

SumatraPDF is a multi-format reader for Windows. In 3.5.2 and earlier, an attacker-controlled SyncTeX source filename is substituted for the %f placeholder in an external editor command line without safe Windows argument quoting, and the resulting command line is passed to CreateProcessW(). A user with an external editor configured or auto-detected who opens a PDF with a crafted .synctex.gz file and invokes inverse search can inject command-line flags; the resulting impact depends on the target editor interpreting those flags and can include unintended editor actions or code execution through a malicious extension. No broader impact is claimed beyond the advisory-supported conditions. No fixed version is available as of this review.

Weakness: CWE-88 (Improper Neutralization of Argument Delimiters in a Command), CWE-20 (Improper Input Validation)

## Which versions are affected by CVE-2026-107734?


## How do I fix CVE-2026-107734?

No fix has been published for CVE-2026-107734 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-107734 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-107734 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-107734 and fix it if it is affected.

What it is: CVE-2026-107734 is a high-severity command injection vulnerability in sumatrapdfreader sumatrapdf, published on 8 Oct 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: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-107734 exists.

Affected product: sumatrapdfreader sumatrapdf. 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-2026-107734/ (Markdown: https://insights.sbomify.com/CVE-2026-107734/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-107734
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-107734
- OSV: https://osv.dev/vulnerability/CVE-2026-107734

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-107734/
Summaries are generated and may contain mistakes; the official description above is the record.