# CVE-2026-107733: SumatraPDF: Null-pointer dereference in `CmdExec` when no document tab is open

> A local attacker can crash SumatraPDF by sending specific messages when no document is open, causing denial of service.

- **Severity:** Medium 6.8 (`CVSS:4.0/AV:L/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:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Oct 2026
- **Updated:** 14 Oct 2026
- **Also known as:** GHSA-p2ph-2rvm-q37m

## What is CVE-2026-107733?

CVE-2026-107733 is a medium-severity vulnerability in sumatrapdfreader sumatrapdf, published on 8 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

SumatraPDF is a multi-format reader for Windows. In 3.6.1 and earlier, FrameOnCommand() handles CmdExec by passing a null current-tab pointer to RunWithExe(), which dereferences WindowTab::filePath. A local process in the same interactive Windows session, at an integrity level greater than or equal to SumatraPDF's under Windows UIPI, can dispatch CmdExec over DDE or WM_COPYDATA while no document tab is open, causing abrupt process termination and loss of unsaved state. No broader impact is claimed beyond the advisory-supported conditions. No fixed version is available as of this review.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2026-107733?


## How do I fix CVE-2026-107733?

No fix has been published for CVE-2026-107733 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-107733 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-107733 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-107733 and fix it if it is affected.

What it is: CVE-2026-107733 is a medium-severity vulnerability in sumatrapdfreader sumatrapdf, published on 8 Oct 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-107733 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-2026-107733/ (Markdown: https://insights.sbomify.com/CVE-2026-107733/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-107733
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-107733
- OSV: https://osv.dev/vulnerability/CVE-2026-107733

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-107733/
Summaries are generated and may contain mistakes; the official description above is the record.