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Fencer Intel
critical 9.8

CVE-2021-20314 json

Stack buffer overflow in libspf2 versions below 1.2.11 when processing certain SPF macros can lead to Denial of service and potentially cod…

published 5y ago modified 4mo ago also EUVD-2021-7739

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
2.8%
EPSS 2.8% chance of exploitation in 30 days, percentile 86%
public exploits
0
none known

Summary

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.

Patch / fix

  • libspf2 libspf2 1.2.11
  • libspf2 Debian 14, Debian 13, Debian 12 1.2.10-7.1

debian advisories DEBIAN-CVE-2021-20314

  • libspf2 Ubuntu 20.04 LTS 1.2.10-7+deb9u2build0.20.04.1
  • libspf2 Ubuntu Pro 16.04 LTS 1.2.10-6ubuntu0.1~esm1
  • libspf2 Ubuntu Pro 18.04 LTS 1.2.10-7ubuntu0.18.04.1~esm1

ubuntu advisories UBUNTU-CVE-2021-20314

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • libspf2 openSUSE Tumbleweed 0.01-5.3
  • libspf2 Package Hub 15 SP3, Package Hub 15 SP2, Package Hub 15 SP1 +2 more 1.2.10-bp153.5.1

opensuse advisories openSUSE-SU-2024:10995-1openSUSE-SU-2021:1187-1

  • libspf2 Alpine 3.24, Alpine 3.23, Alpine 3.22 +11 more 1.2.10-r5
  • libspf2 Alpine 3.24, Alpine 3.23, Alpine 3.22 +1 more 1.2.11-r4

alpine advisories ALPINE-CVE-2021-20314

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • libspf2 Arch Linux 1.2.10-7

arch linux advisories AVG-2280

Is CVE-2021-20314 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2021-20314 updated cvss 7.6

libspf2: stack buffer overflow when processing SPF explanation macros

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.83% chance of exploitation in the next 30 days, higher than 86% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 7.5 AV:N/AC:L/Au:N/C:P/I:P/A:P

Affected products

  • n/a libspf2

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.