Is CVE-2026-26312 actively exploited?

A proof-of-concept exploit is publicly available for CVE-2026-26312, but active exploitation has not been confirmed.

Can CVE-2026-26312 be exploited remotely?

Yes. CVE-2026-26312 is exploitable remotely over the network (CVSS attack vector: Network).

What is the CVSS score of CVE-2026-26312?

CVE-2026-26312 has a CVSS score of 6.5 (MEDIUM) and an EPSS exploitation probability of 0.05%.

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MEDIUMPOC

CVE-2026-26312

CWE-770Published: February 19, 2026· Updated: Feb 20, 2026

6.5

CVSS v3.1

EPSS:0.04%probability of exploitation in 30 daysPercentile:12.8th

Official Description

Stalwart is a mail and collaboration server. A denial-of-service vulnerability exists in Stalwart Mail Server versions 0.13.0 through 0.15.4 where accessing a specially crafted email containing malformed nested `message/rfc822` MIME parts via IMAP or JMAP causes excessive CPU and memory consumption, potentially leading to an out-of-memory condition and server crash. The malformed structure causes the `mail-parser` crate to produce cyclical references in its parsed representation, which Stalwart then follows indefinitely. Version 0.15.5 contains a patch.

NVD Source

Technical Analysis

CVE-2026-26312 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

Exploitation requires low privileges, which limits the exposure to scenarios where an attacker has already gained initial access.

A successful exploit results in availability disruption (denial of service), with a CVSS base score of 6.5.

A proof-of-concept (PoC) exploit exists for CVE-2026-26312. While not yet confirmed in active campaigns, the availability of PoC code increases exploitation risk substantially.