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.

Affects v5.0.8 through v6.6.6.
Published: 2026-09-21
Score: 8.1 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

Vendor Workaround

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.

Tracking

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Advisories

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History

Mon, 21 Sep 2026 16:45:00 +0000

Type Values Removed Values Added
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. 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. Affects v5.0.8 through v6.6.6.

Mon, 21 Sep 2026 15:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Mon, 21 Sep 2026 14:30:00 +0000

Type Values Removed Values Added
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.
Title Fetchmail: fetchmail: stack-based buffer overflow in ntlm authentication (fetchmail-sa-2026-01)
First Time appeared Redhat
Redhat enterprise Linux
Weaknesses CWE-121
CPEs cpe:/o:redhat:enterprise_linux:10
cpe:/o:redhat:enterprise_linux:6
cpe:/o:redhat:enterprise_linux:7
cpe:/o:redhat:enterprise_linux:8
cpe:/o:redhat:enterprise_linux:9
Vendors & Products Redhat
Redhat enterprise Linux
References
Metrics cvssV3_1

{'score': 8.1, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'}

Subscriptions

Redhat Enterprise Linux
cve-icon MITRE

Status: PUBLISHED

Assigner: redhat

Published:

Updated: 2026-09-21T16:29:57.831Z

Reserved: 2026-09-21T01:48:54.590Z

Link: CVE-2026-94184

cve-icon Vulnrichment

Updated: 2026-09-21T14:39:04.468Z

cve-icon NVD

Status : Received

Published: 2026-09-21T15:17:38.547

Modified: 2026-09-21T17:19:19.970

Link: CVE-2026-94184

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-21T17:30:18Z

Weaknesses