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
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| 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 | — | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | fetchmail | 6.6.8-1 | — |
| Debian 13 | fetchmail | No fix yet | — |
| Debian 12 | fetchmail | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | fetchmail | 6.6.6-1ubuntu0.1 | USN-9013-1 |
| Ubuntu 26.04 LTS | fetchmail | 6.6.2-2ubuntu0.1 | USN-9013-1 |
| Ubuntu 24.04 LTS | fetchmail | 6.4.38-1ubuntu4.2 | USN-9013-1 |
| Ubuntu 22.04 LTS | fetchmail | 6.4.27-1ubuntu0.2 | USN-9013-1 |
Show 3 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 20.04 LTS | fetchmail | 6.4.2-2ubuntu0.1~esm1 | USN-9013-1 |
| Ubuntu Pro 18.04 LTS | fetchmail | 6.3.26-3ubuntu0.1~18.04.1+esm1 | USN-9013-1 |
| Ubuntu Pro 16.04 LTS | fetchmail | 6.3.26-2ubuntu0.1~esm1 | USN-9013-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10 | fetchmail | 6.4.38-3.el10_2.1 | RHSA-2026:98583, RHSA-2026:85959 |
| RHEL 9 | fetchmail | 6.4.24-1.el9_8.1 | RHSA-2026:98480, RHSA-2026:86981 |
| RHEL 8 | fetchmail | 6.4.24-1.el8_10.1 | RHSA-2026:86982 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | fetchmail | 6.4.38-3.el10_2.1 | ALSA-2026:85959 |
| AlmaLinux 9 | fetchmail | 6.4.24-1.el9_8.1 | ALSA-2026:86981 |
| AlmaLinux 8 | fetchmail | 6.4.24-1.el8_10.1 | ALSA-2026:86982 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | fetchmail | 6.4.38-3.el10_2.1 | RLSA-2026:98583, RLSA-2026:85959 |
| Rocky Linux 9 | fetchmail | 6.4.24-1.el9_8.1 | RLSA-2026:98480, RLSA-2026:86981 |
| Rocky Linux 8 | fetchmail | 6.4.24-1.el8_10.1 | RLSA-2026:86982 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | fetchmail | 6.4.22-150600.35.6.1 | SUSE-SU-2026:4604-1 |
| SLES 15 SP6 | fetchmail | 6.4.22-150600.35.6.1 | SUSE-SU-2026:4604-1 |
| SLES 15 SP5 | fetchmail | 6.4.22-150000.20.32.1 | SUSE-SU-2026:4605-1 |
| SLES 15 SP4 | fetchmail | 6.4.22-150000.20.32.1 | SUSE-SU-2026:4605-1 |
| SLES 12 SP5 | fetchmail | 6.3.26-13.24.1 | SUSE-SU-2026:4567-1 |
Show 7 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | fetchmail | 6.5.2-160000.4.1 | SUSE-SU-2026:24221-1 |
| SLES for SAP 15 SP6 | fetchmail | 6.4.22-150600.35.6.1 | SUSE-SU-2026:4604-1 |
| SLES for SAP 15 SP5 | fetchmail | 6.4.22-150000.20.32.1 | SUSE-SU-2026:4605-1 |
| SLES for SAP 15 SP4 | fetchmail | 6.4.22-150000.20.32.1 | SUSE-SU-2026:4605-1 |
| SLES 16.0 | fetchmail | 6.5.2-160000.4.1 | SUSE-SU-2026:24221-1 |
| SLE HPC 15 SP5 | fetchmail | 6.4.22-150000.20.32.1 | SUSE-SU-2026:4605-1 |
| SLE HPC 15 SP4 | fetchmail | 6.4.22-150000.20.32.1 | SUSE-SU-2026:4605-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | fetchmail | 6.6.8-1.1 | openSUSE-SU-2026:12115-1 |
| openSUSE Leap 16.0 | fetchmail | 6.5.2-160000.4.1 | openSUSE-SU-2026:22077-1 |
Amazon Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Amazon Linux 2023 | fetchmail | 6.5.7-1.amzn2023.0.1 | ALAS2023-2026-3186 |
| Amazon Linux 2 | fetchmail | 6.3.24-7.amzn2.0.3 | ALAS2-2026-3981 |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | fetchmail | No fix yet | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | fetchmail | 6.4.38-3.el10_2.1 | ELSA-2026-85959 |
| Oracle Linux 9 | fetchmail | 6.4.24-1.el9_8.1 | ELSA-2026-86981 |
| Oracle Linux 8 | fetchmail | 6.4.24-1.el8_10.1 | ELSA-2026-86982 |
Advisories 26
- RHSA-2026:98583 Red Hat Security Advisory: fetchmail security update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RHSA-2026:98480 Red Hat Security Advisory: fetchmail security update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RHSA-2026:86981 Red Hat Security Advisory: fetchmail security update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RHSA-2026:86982 Red Hat Security Advisory: fetchmail security update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RHSA-2026:85959 Red Hat Security Advisory: fetchmail security update Red Hat Security Advisories (RHSA) · Nov 13, 2026
- RLSA-2026:98583 Moderate: fetchmail security update Rocky Linux Security Advisories · Nov 13, 2026
- WID-SEC-2026-3495 fetchmail: Schwachstelle ermöglicht Codeausführung BSI CERT-Bund (WID) · Nov 12, 2026
- RLSA-2026:98480 Moderate: fetchmail security update Rocky Linux Security Advisories · Nov 12, 2026
- USN-9013-1 fetchmail vulnerabilities Ubuntu Security Notices (USN) · Nov 11, 2026
- ALSA-2026:86981 Moderate: fetchmail security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:85959 Moderate: fetchmail security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:86982 Moderate: fetchmail security update AlmaLinux Security Advisories · Oct 29, 2026
- RLSA-2026:85959 Moderate: fetchmail security update Rocky Linux Security Advisories · Oct 22, 2026
- RLSA-2026:86981 Moderate: fetchmail security update Rocky Linux Security Advisories · Oct 22, 2026
- RLSA-2026:86982 Moderate: fetchmail security update Rocky Linux Security Advisories · Oct 22, 2026
- SUSE-SU-2026:24221-1 Security update for fetchmail SUSE / openSUSE Security Updates · Oct 21, 2026
- ELSA-2026-86981 Moderate: fetchmail security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Oct 21, 2026
- ELSA-2026-86982 Moderate: fetchmail security update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Oct 21, 2026
- ELSA-2026-85959 Moderate: fetchmail security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Oct 20, 2026
- openSUSE-SU-2026:22077-1 Security update for fetchmail SUSE / openSUSE Security Updates · Oct 19, 2026
- openSUSE-SU-2026:12115-1 fetchmail-6.6.8-1.1 on GA media SUSE / openSUSE Security Updates · Oct 14, 2026
- ALAS2-2026-3981 Important: fetchmail security update (Amazon Linux 2) Amazon Linux Security Center (ALAS) · Oct 12, 2026
- ALAS2023-2026-3186 Important: fetchmail security update (Amazon Linux 2023) Amazon Linux Security Center (ALAS) · Oct 12, 2026
- SUSE-SU-2026:4605-1 Security update for fetchmail SUSE / openSUSE Security Updates · Oct 9, 2026
- SUSE-SU-2026:4604-1 Security update for fetchmail SUSE / openSUSE Security Updates · Oct 9, 2026
- SUSE-SU-2026:4567-1 Security update for fetchmail SUSE / openSUSE Security Updates · Oct 8, 2026
References
- RHSA-2026:85959 vendor-advisory
- RHSA-2026:86981 vendor-advisory
- RHSA-2026:86982 vendor-advisory
- RHSA-2026:98480 vendor-advisory
- RHSA-2026:98583 vendor-advisory
- https://access.redhat.com/security/cve/CVE-2026-94184 vdb-entry
- https://bugzilla.redhat.com/show_bug.cgi?id=2531984
- RHBZ#2537395 issue-tracking
- https://gitlab.com/fetchmail/fetchmail/-/commit/cb5be5c38471eec19e519ace0bc569176317ea92
- https://www.fetchmail.info/fetchmail-SA-2026-01.txt
- https://www.openwall.com/lists/oss-security/2026/06/27/8