Fetchmail: fetchmail: stack-based buffer overflow in ntlm authentication (fetchmail-sa-2026-01)

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-94184
StatePUBLISHED
Assignerredhat
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-21 15:17:38 UTC
Updated2026-09-22 20:17:13 UTC
DescriptionA 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. Affects v5.0.8 through v6.6.6.

Risk And Classification

Problem Types: CWE-121 | CWE-121 Stack-based Buffer Overflow

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Red Hat Red Hat Enterprise Linux 10 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 6 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 7 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 8 Not specified Not specified
CNA Red Hat Red Hat Enterprise Linux 9 Not specified Not specified

References

ReferenceSourceLinkTags
www.fetchmail.info/fetchmail-SA-2026-01.txt [email protected] www.fetchmail.info
www.openwall.com/lists/oss-security/2026/06/27/8 [email protected] www.openwall.com
bugzilla.redhat.com/show_bug.cgi [email protected] bugzilla.redhat.com
gitlab.com/fetchmail/fetchmail/-/commit/cb5be5c38471eec19e519ace0bc56917... [email protected] gitlab.com
access.redhat.com/security/cve/CVE-2026-94184 [email protected] access.redhat.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Upstream acknowledges Tristan Madani as the original reporter. (en)

Additional Advisory Data

SourceTimeEvent
CNA2026-09-17T00:00:00.000ZReported to Red Hat.
CNA2026-06-27T00:00:00.000ZMade public.

Workarounds

CNA: Rebuild fetchmail without --enable-NTLM (omit NTLM at configure time), or upgrade to fetchmail 6.6.7 or later. Confirm with `fetchmail -V` that the build does not list +NTLM.

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