What’s Vulnerable › Vulnerabilities

CVE-2020-36326

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 3.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2021-04-28 · updated 2026-06-17
• Weakness: CWE-502

Description

PHPMailer 6.1.8 through 6.4.0 allows object injection through Phar Deserialization via addAttachment with a UNC pathname. NOTE: this is similar to CVE-2018-19296, but arose because 6.1.8 fixed a functionality problem in which UNC pathnames were always considered unreadable by PHPMailer, even in safe contexts. As an unintended side effect, this fix eliminated the code that blocked addAttachment exploitation.

Affected products

• Phpmailer Project Phpmailer: from 6.1.8 through 6.4.0
• WordPress: from 3.7 before 3.7.36; from 3.8 before 3.8.36; from 3.9 before 3.9.34; from 4.0 before 4.0.33; from 4.1 before 4.1.33; from 4.2 before 4.2.30 — fixed in 3.7.36, 3.8.36, 3.9.34, 4.0.33, 4.1.33, 4.2.30

How to fix

Upgrade to a fixed version: WordPress 3.7.36, 3.8.36, 3.9.34, 4.0.33. Check the vendor advisory for mitigations.

References

• https://github.com/PHPMailer/PHPMailer/commit/e2e07a355ee8ff36aba21d0242c5950c56e4c6f9
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3B5WDPGUFNPG4NAZ6G4BZX43BKLAVA5B/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KPU66INRFY5BQ3ESVPRUXJR4DXQAFJVT/
• https://github.com/PHPMailer/PHPMailer/commit/e2e07a355ee8ff36aba21d0242c5950c56e4c6f9
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3B5WDPGUFNPG4NAZ6G4BZX43BKLAVA5B/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KPU66INRFY5BQ3ESVPRUXJR4DXQAFJVT/

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