Fetchmail: fetchmail: stack-based buffer overflow in ntlm authentication (fetchmail-sa-2026-01)
CVE-2026-94184 · published 21 Sept 2026
How serious is it
- Severity: high, CVSS score 8.1 out of 10.
- No exploit prediction (EPSS) score yet.
- Not on the CISA list of exploited vulnerabilities.
- No public exploit in Exploit-DB.
Is your app affected by CVE-2026-94184?
Paste this prompt into Claude Code, Cursor or any AI coding tool: it runs a free Shippable scan of your project and fixes what it finds. Built with Lovable, Bolt or v0? Scan your live app. Or upload your package file.
Who is affected
- Red Hat Red Hat Enterprise Linux 10
- Red Hat Red Hat Enterprise Linux 8
- Red Hat Red Hat Enterprise Linux 9
- Red Hat Red Hat Enterprise Linux 6
- Red Hat Red Hat Enterprise Linux 7
How to check
- Find out whether you run the affected product and which version, then compare it with the versions above.
How to fix
Copies a prompt for Claude Code, Cursor or Codex that asks it to check whether you run this product.
- Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
- If a vulnerable version was live, check your logs and rotate the secrets that server could read.
The advisory
A stack-based buffer overflow flaw was found in fetchmail when built with NTLM support. A malicious or compromised mail server advertising NTLM authentication can send a crafted Type 2 challenge that causes fetchmail to write past a fixed stack buffer while building the NTLM authenticate response. This may lead to remote code execution depending on stack-frame layout, or to authentication failure or process termination under memory hardening.
Check your whole app
Dependencies are only half of it. Free and read-only: before you push, run npx shippable-dev scan localhost:3000 in your project folder, no account needed. For your live app, you prove it's yours with a one-line tag first.
References
- access.redhat.com/errata/RHSA-2026:85959
- access.redhat.com/errata/RHSA-2026:86981
- access.redhat.com/errata/RHSA-2026:86982
- access.redhat.com/security/cve/CVE-2026-94184
- bugzilla.redhat.com/show_bug.cgi?id=2531984
- bugzilla.redhat.com/show_bug.cgi?id=2537395
- gitlab.com/fetchmail/fetchmail/-/commit/cb5be5c38471eec19e519ace0bc569176317ea92
- www.fetchmail.info/fetchmail-SA-2026-01.txt
- www.openwall.com/lists/oss-security/2026/06/27/8
Merged from CVE List. Last updated 27 Oct 2026. All vulnerabilities · RSS · JSON