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Vulnerability record · CVE-2020-36326 · published 28 April 2021

CVE-2020-36326: Phpmailer project phpmailer deserialization of untrusted data vulnerability

Phpmailer Project · Phpmailer

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.

9.8 CVSS 3.1 Critical EPSS 3.1% · top 12.6% CWE-502 · Deserialization of untrusted data
9.8CVSS 3.1 base score, v2 7.5
3.1%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
6References
17 Jun 2026Last modified by NVD

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.

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

Affected products

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

References

LinkTags
https://github.com/PHPMailer/PHPMailer/commit/e2e07a355ee8ff36aba21d0242c5950c56e4c6f9 PatchThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3B5WDPGUFNPG4NAZ6G4BZX4
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KPU66INRFY5BQ3ESVPRUXJR
https://github.com/PHPMailer/PHPMailer/commit/e2e07a355ee8ff36aba21d0242c5950c56e4c6f9 PatchThird Party Advisory
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/3B5WDPGUFNPG4NAZ6G4BZX4
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/KPU66INRFY5BQ3ESVPRUXJR

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

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Source: NIST National Vulnerability Database (record CVE-2020-36326), CISA KEV, FIRST EPSS (scores of 2026-10-11). This page is refreshed as NVD updates the record.