CVE-2021-20314

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 2.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-08-12 · updated 2026-06-17
Weakness: CWE-787

Description

Stack buffer overflow in libspf2 versions below 1.2.11 when processing certain SPF macros can lead to Denial of service and potentially code execution via malicious crafted SPF explanation messages.

Affected products

Fedoraproject Fedora: 33, 34, 35
Libspf2: before 1.2.11 — fixed in 1.2.11
Red Hat Enterprise Linux: 7.0

How to fix

Upgrade to a fixed version: Libspf2 1.2.11. Check the vendor advisory for mitigations.

References

https://bugzilla.redhat.com/show_bug.cgi?id=1993070
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CMSFT2NJDZ7PATRZSQPAOGSE7JD6ELOB/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GFXJRHPE5OSCPTNA3ZZ4ORDHT4JQH3Y4/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Y6T4HYXXSUQCGJB2ES6X7Q74YYF7V7XU/
https://security.gentoo.org/glsa/202401-22
https://bugzilla.redhat.com/show_bug.cgi?id=1993070
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/CMSFT2NJDZ7PATRZSQPAOGSE7JD6ELOB/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/GFXJRHPE5OSCPTNA3ZZ4ORDHT4JQH3Y4/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/Y6T4HYXXSUQCGJB2ES6X7Q74YYF7V7XU/
https://security.gentoo.org/glsa/202401-22

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