CVE-2026-3889 Spoofing issue in Thunderbird
Medium 6.5
Published
Updated
Check this codebase for CVE-2026-3889 and fix it if it is affected.
What it is: CVE-2026-3889 is a medium-severity vulnerability in Mozilla Thunderbird, published on 24 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-3889 in the wild and no public exploit code.
Affected product: Mozilla Thunderbird. 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-2026-3889/ (Markdown: https://insights.sbomify.com/CVE-2026-3889/index.md)
An attacker can spoof content in Thunderbird, potentially misleading users about the source or nature of displayed information.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-3889?
CVE-2026-3889 is a medium-severity vulnerability in Mozilla Thunderbird, published on 24 Mar 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Spoofing issue in Thunderbird. This vulnerability was fixed in Thunderbird 149 and Thunderbird 140.9.
Weakness: CWE-451
Which versions are affected by CVE-2026-3889?
It affects 1 product.
Products include Mozilla Thunderbird.
How do I fix CVE-2026-3889?
Upgrade to a fixed version.
Is CVE-2026-3889 being exploited?
There is no known exploitation of CVE-2026-3889 in the wild and no public exploit code.
Other vulnerabilities in Mozilla Thunderbird
Sources
Also known as DEBIAN-CVE-2026-3889, GHSA-g3qh-qhp8-8f86, UBUNTU-CVE-2026-3889.