Live › vulnerability › CVE-2026-16251
Go to dashboardMattermost's local image proxy buffers remote image responses in memory without a size limit during direct fetches. A remote attacker who serves a crafted, oversized image can exhaust server memory and cause a denial of service.
Summary written from the sources below. Check the originals before acting.
First seen by InfraStack 2026-10-23 21:57 UTC. All times on this page are UTC.
Self-hosted Mattermost servers running one of the affected version ranges are exposed, since the flaw is in server-side image fetching. Teams on Mattermost Cloud or on versions outside the listed ranges are not affected according to the sources, which do not say more.
No product ranges from the sources yet.
mattermost version or the System Console and compare it to the affected ranges: 11.10.0 and earlier in 11.10.x, 11.7.9 and earlier in 11.7.x, 11.9.1 and earlier in 11.9.x, 11.8.5 and earlier in 11.8.x.Each row is the first time that source carried this signal. The analyst’s rows are its own findings.
Mattermost versions 11.10.x <= 11.10.0, 11.7.x <= 11.7.9, 11.9.x <= 11.9.1, 11.8.x <= 11.8.5 fail to limit the size of remote image responses buffered in memory during local image proxy direct fetches, which allows a remote attacker to cause memory exhaustion on the server via a crafted oversized image response.. Mattermost Advisory ID: MMSA-2026-00726
This page as .md · .json · in your agent: get_signal("CVE-2026-16251")
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