Summary
Christian Herdtweck discovered that Fetchmail incorrectly handled certain
long log messages. A remote attacker could possibly use this issue to cause
Fetchmail to crash, resulting in a denial of service. This issue only
affected Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, and Ubuntu 20.04 LTS.
(CVE-2021-36386)
It was discovered that the Fetchmail SMTP client incorrectly handled
certain status code messages. An attacker controlling a malicious server
could possibly use this issue to cause Fetchmail to crash, resulting in a
denial of service. This issue only affected Ubuntu 16.04 LTS, Ubuntu 18.04
LTS, and Ubuntu 20.04 LTS. (CVE-2025-61962)
Tristan Madani discovered that Fetchmail incorrectly handled certain NTLM
authentication challenges. A remote attacker could possibly use this issue
to cause Fetchmail to crash, resulting in a denial of service, or possibly
execute arbitrary code. The default compiler options for affected releases
should reduce the vulnerability to a denial of service. (CVE-2026-94184)
Fixed packages 7
| Release | Package | Fixed in |
|---|---|---|
| Ubuntu · 22.04 LTS 22.04:LTS | fetchmail | 6.4.27-1ubuntu0.2 |
| Ubuntu · 24.04 LTS 24.04:LTS | fetchmail | 6.4.38-1ubuntu4.2 |
| Ubuntu · 26.04 LTS 26.04:LTS | fetchmail | 6.6.2-2ubuntu0.1 |
| Ubuntu · 26.10 | fetchmail | 6.6.6-1ubuntu0.1 |
| Ubuntu · Pro 16.04 LTS Pro:16.04:LTS | fetchmail | 6.3.26-2ubuntu0.1~esm1 |
| Ubuntu · Pro 18.04 LTS Pro:18.04:LTS | fetchmail | 6.3.26-3ubuntu0.1~18.04.1+esm1 |
| Ubuntu · Pro 20.04 LTS Pro:20.04:LTS | fetchmail | 6.4.2-2ubuntu0.1~esm1 |
Vulnerabilities 3
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Medium 5.9
In fetchmail before 6.5.6, the SMTP client can crash when authenticating upon receiving a 334 status code in a malforme…
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Medium 5.3
Fetchmail: fetchmail: stack-based buffer overflow in ntlm authentication (fetchmail-sa-2026-01)
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 b…
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Unscored —
report_vbuild in report.c in Fetchmail before 6.4.20 sometimes omits initialization of the vsnprintf va_list argument, …