How severe is CVE-2026-26312?

CVE-2026-26312 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-26312 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (27th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-26312?

CVE-2026-26312 affects Stalw Stalwart. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-26312?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-26312 have an EU (EUVD) identifier?

Yes. CVE-2026-26312 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8304.

When was CVE-2026-26312 published?

CVE-2026-26312 was published on 2026-02-19 and last updated on 2026-06-17.

CVE-2026-26312

CVE-2026-26312 is a medium-severity vulnerability in Stalw Stalwart with a CVSS 3.x base score of 6.5. 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-770.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
EPSS exploit prediction: 0% (27th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-8304
Weakness: CWE-770
Affected product: Stalw Stalwart
Published: 2026-02-19
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-26312?: 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.
How severe is CVE-2026-26312?: CVE-2026-26312 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-26312 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (27th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-26312?: CVE-2026-26312 affects Stalw Stalwart. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-26312?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-26312 have an EU (EUVD) identifier?: Yes. CVE-2026-26312 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-8304.
When was CVE-2026-26312 published?: CVE-2026-26312 was published on 2026-02-19 and last updated on 2026-06-17.

References

https://github.com/stalwartlabs/stalwart/security/advisories/GHSA-jm95-876q-c9gw

Affected products (1)

cpe:2.3:a:stalw:stalwart:*:*:*:*:*:*:*:*

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