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Fencer Intel
critical 9.8

CVE-2020-28024 json

Exim 4 before 4.94.2 allows Buffer Underwrite that may result in unauthenticated remote attackers executing arbitrary commands, because smt…

published 5y ago modified 4mo ago also EUVD-2020-20515

cvss
9.8
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
4.2%
EPSS 4.2% chance of exploitation in 30 days, percentile 90%
public exploits
0
none known

Summary

Exim 4 before 4.94.2 allows Buffer Underwrite that may result in unauthenticated remote attackers executing arbitrary commands, because smtp_ungetc was only intended to push back characters, but can actually push back non-character error codes such as EOF.

Patch / fix

  • exim exim 4.94.2
  • exim4 Debian 14, Debian 13, Debian 12 4.94.2-1

debian advisories DEBIAN-CVE-2020-28024

  • exim4 Ubuntu 18.04 LTS 4.90.1-1ubuntu1.8
  • exim4 Ubuntu 20.04 LTS 4.93-13ubuntu1.5
  • exim4 Ubuntu Pro 14.04 LTS 4.82-3ubuntu2.4+esm3
  • exim4 Ubuntu Pro 16.04 LTS 4.86.2-2ubuntu2.6+esm1

ubuntu advisories UBUNTU-CVE-2020-28024

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

  • exim openSUSE Tumbleweed 4.94.2-4.2
  • exim Package Hub 15 SP2 4.94.2-bp152.6.4.1
  • libspf2 Package Hub 15 SP2 1.2.10-bp152.5.1
  • exim Package Hub 15 SP1 4.94.2-bp151.2.4.1
  • libspf2 Package Hub 15 SP1 1.2.10-bp151.4.1
  • exim openSUSE Leap 15.2 4.94.2-lp152.8.3.1

opensuse advisories openSUSE-SU-2024:10746-1openSUSE-SU-2021:0754-1openSUSE-SU-2021:0753-1openSUSE-SU-2021:0677-1

  • exim Alpine 3.24, Alpine 3.23, Alpine 3.22 +9 more 4.94.2-r0

alpine advisories ALPINE-CVE-2020-28024

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

  • exim Arch Linux 4.94.2-1

arch linux advisories AVG-1911

Is CVE-2020-28024 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.

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Exploit prediction

4.15% chance of exploitation in the next 30 days, higher than 90% 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

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.