What’s Vulnerable › Vulnerabilities

CVE-2020-28020

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 7.9% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-05-06 · updated 2026-06-17
• Weakness: CWE-190

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.

Affected products

• Exim: from 4.00 before 4.92 — fixed in 4.92

How to fix

Upgrade to a fixed version: Exim 4.92. Check the vendor advisory for mitigations.

References

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

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