Fetchmail: fetchmail: stack-based buffer overflow in ntlm authentication (fetchmail-sa-2026-01)
Summary
| CVE | CVE-2026-94184 |
|---|---|
| State | PUBLISHED |
| Assigner | redhat |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-21 15:17:38 UTC |
| Updated | 2026-10-21 15:17:19 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 8.1 HIGH from ADP
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS: 0.008410000 probability, percentile 0.574050000 (date 2026-10-21)
Problem Types: CWE-121 | CWE-121 Stack-based Buffer Overflow
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | ADP | DECLARED | 8.1 | HIGH | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | [email protected] | Secondary | 5.3 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |
| 3.1 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | Secondary | 8.1 | HIGH | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H |
| 3.1 | CNA | CVSS | 5.3 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
HighPrivileges Required
NoneUser Interaction
NoneScope
UnchangedConfidentiality
HighIntegrity
HighAvailability
HighCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Red Hat | Red Hat Enterprise Linux 10 | unaffected 0:6.4.38-3.el10_2.1 * rpm | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 8 | unaffected 0:6.4.24-1.el8_10.1 * rpm | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 9 | unaffected 0:6.4.24-1.el9_8.1 * rpm | 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 |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| access.redhat.com/errata/RHSA-2026:86982 | [email protected] | access.redhat.com | |
| bugzilla.redhat.com/show_bug.cgi | [email protected] | bugzilla.redhat.com | |
| www.fetchmail.info/fetchmail-SA-2026-01.txt | [email protected] | www.fetchmail.info | |
| www.openwall.com/lists/oss-security/2026/09/23/1 | af854a3a-2127-422b-91ae-364da2661108 | www.openwall.com | |
| www.openwall.com/lists/oss-security/2026/06/27/8 | [email protected] | www.openwall.com | |
| access.redhat.com/errata/RHSA-2026:86981 | [email protected] | access.redhat.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/errata/RHSA-2026:85959 | [email protected] | access.redhat.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
| Source | Time | Event |
|---|---|---|
| CNA | 2026-09-17T00:00:00.000Z | Reported to Red Hat. |
| CNA | 2026-06-27T00:00:00.000Z | Made public. |
Workarounds
CNA: Rebuild fetchmail without --enable-NTLM (omit NTLM at configure time). Confirm with `fetchmail -V` that the build does not list +NTLM.
There are currently no legacy QID mappings associated with this CVE.