CVE-2026-4054 — SVG content served through Mattermost image proxy despite Content-Type restrictions causes client-side denial of servi…

CVE-2026-4054

SVG content served through Mattermost image proxy despite Content-Type restrictions causes client-side denial of service PUBLISHED

Description (CNA)

Mattermost versions 11.5.x <= 11.5.1, 10.11.x <= 10.11.13, 11.4.x <= 11.4.3 Fail to validate the response body of proxied images, which allows a remote attacker to enact client-side DoS via an SVG file served from an attacker-controlled origin under a non-SVG Content-Type header (e.g. image/png) embedded in an og:image meta tag or Markdown image link.. Mattermost Advisory ID: MMSA-2026-00630

Affected (CNA)

Vendor / product	Versions
Mattermost / Mattermost	affected 11.5.0 through 11.5.1; affected 10.11.0 through 10.11.13; affected 11.4.0 through 11.4.3; unaffected 11.6.0; unaffected 11.5.2; unaffected 10.11.14; unaffected 11.4.4

CWE

CWE-754

References

https://mattermost.com/security-updates

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.