CVE-2026-43864 Null dereference in mutt
Low 2.5
Published
Updated
Check this codebase for CVE-2026-43864 and fix it if it is affected.
What it is: CVE-2026-43864 is a low-severity vulnerability in mutt, published on 4 May 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-2026-43864 in the wild and no public exploit code.
Affected product: mutt. 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-2026-43864/ (Markdown: https://insights.sbomify.com/CVE-2026-43864/index.md)
A NULL pointer dereference in Mutt's signature summary display can cause the application to crash, leading to denial of service.
- 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
What is CVE-2026-43864?
CVE-2026-43864 is a low-severity vulnerability in mutt, published on 4 May 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
mutt before 2.3.2 has a show_sig_summary NULL pointer dereference.
Weakness: CWE-476
Which versions are affected by CVE-2026-43864?
How do I fix CVE-2026-43864?
Upgrade to a fixed version.
Is CVE-2026-43864 being exploited?
There is no known exploitation of CVE-2026-43864 in the wild and no public exploit code.
Sources
Also known as AZL-85599, DEBIAN-CVE-2026-43864, GHSA-gwv2-2c9f-hmfv, UBUNTU-CVE-2026-43864.