SMTP: Microsoft Exchange Server X-MS-Exchange-P2FromRegexMatch Header Security Feature Bypass

This signature detects attempts to exploit a known vulnerability against Microsoft. A successful attack can lead to security bypass.

Short Name
SMTP:VULN:MS-EX-SR-PRPM-SBYPSS
Severity
Minor
Recommended
True
Recommended Action
None
Category
SMTP
Keywords
Bypass CVE-2026-21527 Exchange Feature Header Microsoft Security Server X-MS-Exchange-P2FromRegexMatch
Release Date
03/17/2026
Supported Platforms

mx-19.3

vmx-19.3

vsrx-19.2

srx-19.3

srx-branch-19.3

vsrx3bsd-19.2

srx-19.4

vsrx3bsd-19.4

srx-branch-19.4

vsrx-19.4

vmx-19.4

mx-19.4

srxevo-25.4

vsrx-26.2

srx-26.2

srx-branch-26.2

vsrx3bsd-26.2

mx-12.3

srx-12.3

srx-branch-12.3

vsrx-12.3

Sigpack Version
3934
False Positive
Unknown

Found a potential security threat?