What’s Vulnerable › Vulnerabilities

CVE-2020-28018

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 56.5% 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-416

Description

Exim 4 before 4.94.2 allows Use After Free in smtp_reset in certain situations that may be common for builds with OpenSSL.

Affected products

• Exim: from 4.90 before 4.94.2 — fixed in 4.94.2

How to fix

Upgrade to a fixed version: Exim 4.94.2. Check the vendor advisory for mitigations.

References

• http://www.openwall.com/lists/oss-security/2021/05/11/14
• http://www.openwall.com/lists/oss-security/2021/05/11/15
• http://www.openwall.com/lists/oss-security/2021/05/11/17
• http://www.openwall.com/lists/oss-security/2021/05/11/5
• http://www.openwall.com/lists/oss-security/2021/05/11/6
• http://www.openwall.com/lists/oss-security/2021/05/12/2
• http://www.openwall.com/lists/oss-security/2021/05/12/3
• https://www.exim.org/static/doc/security/CVE-2020-qualys/CVE-2020-28018-OCORK.txt
• http://www.openwall.com/lists/oss-security/2021/05/11/14
• http://www.openwall.com/lists/oss-security/2021/05/11/15
• http://www.openwall.com/lists/oss-security/2021/05/11/17
• http://www.openwall.com/lists/oss-security/2021/05/11/5

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