How severe is CVE-2026-26246?

CVE-2026-26246 has a CVSS 3.x base score of 4.3, 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 low.

Is CVE-2026-26246 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-26246?

CVE-2026-26246 affects Mattermost Mattermost Server. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-26246?

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

Does CVE-2026-26246 have an EU (EUVD) identifier?

Yes. CVE-2026-26246 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12417.

When was CVE-2026-26246 published?

CVE-2026-26246 was published on 2026-03-16 and last updated on 2026-06-17.

CVE-2026-26246

CVE-2026-26246 is a medium-severity vulnerability in Mattermost Mattermost Server with a CVSS 3.x base score of 4.3. 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-789.

Key facts

Severity: Medium (CVSS 3.x base score 4.3)
EPSS exploit prediction: 0% (13th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-12417
Weakness: CWE-789
Affected product: Mattermost Mattermost Server
Published: 2026-03-16
Last modified: 2026-06-17

Description

Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to bound memory allocation when processing PSD image files which allows an authenticated attacker to cause server memory exhaustion and denial of service via uploading a specially crafted PSD file. Mattermost Advisory ID: MMSA-2026-00572

Frequently asked questions

What is CVE-2026-26246?: Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to bound memory allocation when processing PSD image files which allows an authenticated attacker to cause server memory exhaustion and denial of service via uploading a specially crafted PSD file. Mattermost Advisory ID: MMSA-2026-00572
How severe is CVE-2026-26246?: CVE-2026-26246 has a CVSS 3.x base score of 4.3, 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 low.
Is CVE-2026-26246 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (13th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-26246?: CVE-2026-26246 affects Mattermost Mattermost Server. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-26246?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-26246 have an EU (EUVD) identifier?: Yes. CVE-2026-26246 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-12417.
When was CVE-2026-26246 published?: CVE-2026-26246 was published on 2026-03-16 and last updated on 2026-06-17.

References

https://mattermost.com/security-updates

Affected products (1)

cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*

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