What’s Vulnerable › Vulnerabilities

CVE-2021-36386

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 2.6% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-07-30 · updated 2026-06-17
• Weakness: CWE-909

Description

report_vbuild in report.c in Fetchmail before 6.4.20 sometimes omits initialization of the vsnprintf va_list argument, which might allow mail servers to cause a denial of service or possibly have unspecified other impact via long error messages. NOTE: it is unclear whether use of Fetchmail on any realistic platform results in an impact beyond an inconvenience to the client user.

Affected products

• Fedoraproject Fedora: 33, 34
• fetchmail: before 6.4.20 — fixed in 6.4.20

How to fix

Upgrade to a fixed version: fetchmail 6.4.20. Check the vendor advisory for mitigations.

References

• http://www.openwall.com/lists/oss-security/2021/07/28/5
• http://www.openwall.com/lists/oss-security/2021/08/09/1
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AGYO5AHSXTCKA4NQC2Z4H3XMMYNAGC77/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OIXKO6QW3AUHGJVWKJXBCOVBYJUJRBFC/
• https://security.gentoo.org/glsa/202209-14
• https://www.fetchmail.info/fetchmail-SA-2021-01.txt
• https://www.fetchmail.info/security.html
• http://www.openwall.com/lists/oss-security/2021/07/28/5
• http://www.openwall.com/lists/oss-security/2021/08/09/1
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/AGYO5AHSXTCKA4NQC2Z4H3XMMYNAGC77/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/OIXKO6QW3AUHGJVWKJXBCOVBYJUJRBFC/
• https://security.gentoo.org/glsa/202209-14

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