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Vulnerability record · CVE-2020-28020 · published 6 May 2021

CVE-2020-28020: Exim integer overflow vulnerability

Exim · Exim

Exim 4 before 4.92 allows Integer Overflow to Buffer Overflow, in which an unauthenticated remote attacker can execute arbitrary code by leveraging the mishandling of continuation lines during header-length restriction.

9.8 CVSS 3.1 Critical EPSS 7.9% · top 5.5% CWE-190 · Integer overflow
9.8CVSS 3.1 base score, v2 7.5
7.9%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
6References
17 Jun 2026Last modified by NVD

Description

Exim 4 before 4.92 allows Integer Overflow to Buffer Overflow, in which an unauthenticated remote attacker can execute arbitrary code by leveraging the mishandling of continuation lines during header-length restriction.

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

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
http://www.openwall.com/lists/oss-security/2021/07/25/1 Mailing ListThird Party Advisory
http://www.openwall.com/lists/oss-security/2021/08/03/1 Mailing ListThird Party Advisory
https://www.exim.org/static/doc/security/CVE-2020-qualys/CVE-2020-28020-HSIZE.txt PatchThird Party Advisory
http://www.openwall.com/lists/oss-security/2021/07/25/1 Mailing ListThird Party Advisory
http://www.openwall.com/lists/oss-security/2021/08/03/1 Mailing ListThird Party Advisory
https://www.exim.org/static/doc/security/CVE-2020-qualys/CVE-2020-28020-HSIZE.txt PatchThird Party Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2020-28020), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.