How severe is CVE-2020-36326?

CVE-2020-36326 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2020-36326 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (86th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-36326?

CVE-2020-36326 primarily affects Phpmailer Project Phpmailer. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-36326?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2020-36326 published?

CVE-2020-36326 was published on 2021-04-28 and last updated on 2026-06-17.

CVE-2020-36326

CVE-2020-36326 is a critical-severity vulnerability in Phpmailer Project Phpmailer with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-502.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 3% (86th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-502
Affected product: Phpmailer Project Phpmailer
Published: 2021-04-28
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2020-36326?: 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.
How severe is CVE-2020-36326?: CVE-2020-36326 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2020-36326 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 3% (86th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-36326?: CVE-2020-36326 primarily affects Phpmailer Project Phpmailer. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-36326?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2020-36326 published?: CVE-2020-36326 was published on 2021-04-28 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:phpmailer_project:phpmailer:*:*:*:*:*:*:*:*
cpe:2.3:a:wordpress:wordpress:*:*:*:*:*:*:*:*

More vulnerabilities in Phpmailer Project Phpmailer

CVE-2016-10045 — Critical (CVSS 9.8): The isMail transport in PHPMailer before 5.2.20 might allow remote attackers to pass extra parameters to the mail…
CVE-2016-10033 — Critical (CVSS 9.8): The mailSend function in the isMail transport in PHPMailer before 5.2.18 might allow remote attackers to pass extra…
CVE-2018-19296 — High (CVSS 8.8): PHPMailer before 5.2.27 and 6.x before 6.0.6 is vulnerable to an object injection attack.
CVE-2021-3603 — High (CVSS 8.1): PHPMailer 6.4.1 and earlier contain a vulnerability that can result in untrusted code being called (if such code is…
CVE-2021-34551 — High (CVSS 8.1): PHPMailer before 6.5.0 on Windows allows remote code execution if lang_path is untrusted data and has a UNC pathname.
CVE-2020-13625 — High (CVSS 7.5): PHPMailer before 6.1.6 contains an output escaping bug when the name of a file attachment contains a double quote…

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Threat intelligence

Threat-intel indicators referencing this CVE:

64.202.190.35 (ipv4-addr)