CVE-2020-12783

Name: CVE-2020-12783
Creator: NVD / NIST
Published: 2020-05-11T14:15:11.917+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 7.5/10EPSS 4.47%

Last modified Jun 17, 2026

CVE-2020-12783 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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.. EPSS estimates a 4.47% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS Probability

4.47%

90.2th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-125

Affected Software

Vendor	Product	Versions
Exim	Exim	<= 4.93
Fedoraproject	Fedora	31
Fedoraproject	Fedora	32
Debian	Debian Linux	8.0
Debian	Debian Linux	9.0
Debian	Debian Linux	10.0
Canonical	Ubuntu Linux	14.04
Canonical	Ubuntu Linux	16.04
Canonical	Ubuntu Linux	18.04
Canonical	Ubuntu Linux	19.10
Canonical	Ubuntu Linux	20.04

References

http://www.openwall.com/lists/oss-security/2021/05/04/7Exploit, Mailing List, Third Party Advisory
https://bugs.exim.org/show_bug.cgi?id=2571Third Party Advisory
https://git.exim.org/exim.git/commit/57aa14b216432be381b6295c312065b2fd034f86Patch, Third Party Advisory
https://git.exim.org/exim.git/commit/a04174dc2a84ae1008c23b6a7109e7fa3fb7b8b0Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/05/msg00017.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/F6IQQ2SERFUD4WMRSX6XYDNK7Q4GPT7Y/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/M7Z5UG6ZIG32V7M4PP3BCC65C27EWK7G/
https://usn.ubuntu.com/4366-1/Third Party Advisory
https://www.debian.org/security/2020/dsa-4687Third Party Advisory
http://www.openwall.com/lists/oss-security/2021/05/04/7Exploit, Mailing List, Third Party Advisory
https://bugs.exim.org/show_bug.cgi?id=2571Third Party Advisory
https://git.exim.org/exim.git/commit/57aa14b216432be381b6295c312065b2fd034f86Patch, Third Party Advisory
https://git.exim.org/exim.git/commit/a04174dc2a84ae1008c23b6a7109e7fa3fb7b8b0Patch, Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/05/msg00017.htmlMailing List, Third Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/F6IQQ2SERFUD4WMRSX6XYDNK7Q4GPT7Y/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/M7Z5UG6ZIG32V7M4PP3BCC65C27EWK7G/
https://usn.ubuntu.com/4366-1/Third Party Advisory
https://www.debian.org/security/2020/dsa-4687Third Party Advisory

Timeline

Published: May 11, 2020
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2020-12783?

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.

How severe is CVE-2020-12783?

CVE-2020-12783 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 4.47% probability of exploitation in the next 30 days.

How do I fix CVE-2020-12783?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2020-12783?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST