CVE-2025-0431: Enterprise Protection Backslash URL Rewrite Bypass

Severity: medium (CVSS 5.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-03-19 · updated 2026-06-17
Weakness: CWE-790

Description

Enterprise Protection contains a vulnerability in URL rewriting that allows an unauthenticated remote attacker to send an email which bypasses URL protections impacting the integrity of recipient's email. This occurs due to improper filtering of backslashes within URLs and affects all versions of 8.21, 8.20 and 8.18 prior to 8.21.0 patch 5115, 8.20.6 patch 5114 and 8.18.6 patch 5113 respectively.

Affected products

Proofpoint Enterprise Protection: from 8.18.6 before patch 5113; from 8.20.6 before patch 5114; from 8.21.0 before patch 5115 — fixed in patch 5113, patch 5114, patch 5115

How to fix

Upgrade to a fixed version: Proofpoint Enterprise Protection patch 5113, patch 5114, patch 5115. Check the vendor advisory for mitigations.

References

https://www.proofpoint.com/us/security/security-advisories/pfpt-sa-2025-0001

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