CVE-2026-94184: Fetchmail: fetchmail: stack-based buffer overflow in ntlm authentication (fetchmail-sa-2026-01)

Severity: medium (CVSS 5.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-09-21 · updated 2026-10-21
Weakness: CWE-121

Description

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.

Affected products

Red Hat Enterprise Linux 10: all versions — fixed in 0:6.4.38-3.el10_2.1
Red Hat Enterprise Linux 6: all versions
Red Hat Enterprise Linux 7: all versions
Red Hat Enterprise Linux 8: all versions — fixed in 0:6.4.24-1.el8_10.1
Red Hat Enterprise Linux 9: all versions — fixed in 0:6.4.24-1.el9_8.1

How to fix

Upgrade to a fixed version: Red Hat Enterprise Linux 10 0:6.4.38-3.el10_2.1; Red Hat Enterprise Linux 8 0:6.4.24-1.el8_10.1; Red Hat Enterprise Linux 9 0:6.4.24-1.el9_8.1. Check the vendor advisory for mitigations.

References

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