CVE-2026-5735 Memory safety bugs fixed in Firefox 149.0.2 and Thunderbird 149.0.2
High 8.1
Published
Updated
Check this codebase for CVE-2026-5735 and fix it if it is affected.
What it is: CVE-2026-5735 is a high-severity vulnerability in Mozilla Firefox, published on 7 Apr 2026.
Exploitation: There is no known exploitation of CVE-2026-5735 in the wild and no public exploit code.
Affected product: Mozilla Firefox. 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-2026-5735/ (Markdown: https://insights.sbomify.com/CVE-2026-5735/index.md)
- Exploited in the wild
- Not known
- Fix
- Available
What is CVE-2026-5735?
CVE-2026-5735 is a high-severity vulnerability in Mozilla Firefox, published on 7 Apr 2026.
Official description
Memory safety bugs present in Firefox 149.0.1 and Thunderbird 149.0.1. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code. This vulnerability was fixed in Firefox 149.0.2 and Thunderbird 149.0.2.
Which versions are affected by CVE-2026-5735?
It affects 2 products.
Products include Mozilla Firefox, Mozilla Thunderbird.
How do I fix CVE-2026-5735?
Upgrade to a fixed version.
Is CVE-2026-5735 being exploited?
There is no known exploitation of CVE-2026-5735 in the wild and no public exploit code.
Other vulnerabilities in Mozilla Firefox
Sources
Also known as GHSA-rrjf-ccr2-ph7g, UBUNTU-CVE-2026-5735.