# CVE-2026-113868: Uninitialized memory disclosure and out-of-bounds read in POP3 and SMTP NTLM authentication


- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 20 Oct 2026
- **Updated:** 20 Oct 2026
- **Also known as:** DEBIAN-CVE-2026-113868, GHSA-v77j-vmg8-85hq, UBUNTU-CVE-2026-113868

## What is CVE-2026-113868?

CVE-2026-113868 is a medium-severity vulnerability in Mozilla Thunderbird, published on 20 Oct 2026. 

### Official description

When authenticating to a POP3 or SMTP server using NTLM, Thunderbird did not check whether the server's challenge was valid base64. A malicious server could send a challenge that caused Thunderbird to include uninitialized heap memory in its NTLM response, disclosing that memory to the server. A challenge consisting only of base64 padding also caused an out-of-bounds read, crashing Thunderbird. This affected accounts configured to use NTLM or GSSAPI authentication. The uninitialized memory disclosure only affected NTLM. This vulnerability was fixed in Thunderbird 158.0.1 and Thunderbird 153.5.1.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2026-113868?


## How do I fix CVE-2026-113868?

Upgrade to a fixed version.

## Is CVE-2026-113868 being exploited?

There is no known exploitation of CVE-2026-113868 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-113868 and fix it if it is affected.

What it is: CVE-2026-113868 is a medium-severity vulnerability in Mozilla Thunderbird, published on 20 Oct 2026. 
Exploitation: There is no known exploitation of CVE-2026-113868 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-2026-113868/ (Markdown: https://insights.sbomify.com/CVE-2026-113868/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-113868
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-113868
- OSV: https://osv.dev/vulnerability/CVE-2026-113868

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-113868/
Summaries are generated and may contain mistakes; the official description above is the record.