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Fencer Vulns
high 7.5

CVE-2020-12783 json

Exim through 4.93 has an out-of-bounds read in the SPA authenticator that could result in SPA/NTLM authentication bypass in auths/spa.c and…

published 2020-05-11 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-5068

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
4.6%
EPSS 4.6% chance of exploitation in 30 days, percentile 91%
public exploits
0
none known

Summary

Exim through 4.93 has an out-of-bounds read in the SPA authenticator that could result in SPA/NTLM authentication bypass in auths/spa.c and auths/auth-spa.c.

Patch / fix

  • exim4 Debian 14, Debian 13, Debian 12 4.93-16

debian advisories DEBIAN-CVE-2020-12783

  • exim4 Ubuntu 16.04 LTS 4.86.2-2ubuntu2.6
  • exim4 Ubuntu 18.04 LTS 4.90.1-1ubuntu1.5
  • exim4 Ubuntu 20.04 LTS 4.93-13ubuntu1.1
  • exim4 Ubuntu Pro 14.04 LTS 4.82-3ubuntu2.4+esm2

ubuntu advisories UBUNTU-CVE-2020-12783

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 +11 more 4.93-r1

alpine advisories ALPINE-CVE-2020-12783

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

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-2020-12783 updated cvss 7.5

exim: out-of-bounds read in the SPA authenticator can lead to SPA/NTLM authentication bypass in auths/spa.c and auths/auth-spa.c

  • Red Hat Enterprise Linux 5 exim
    affected: no fix planned “Out of support scope”

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

4.55% chance of exploitation in the next 30 days, higher than 91% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • openwall.com http://www.openwall.com/lists/oss-security/2021/05/04/7 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:P/I:N/A:N

Classification

Weakness

References

Sources

Fencer Vulns 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.