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Medium severity6.5NVD Advisory· Published Jul 13, 2026· Updated Jul 13, 2026

CVE-2026-6850

CVE-2026-6850

Description

Mattermost versions 11.7.x <= 11.7.2, 11.6.x <= 11.6.4, 10.11.x <= 10.11.19 fail to validate the length and content of message attachment field values, which allows an authenticated attacker to cause a denial of service for all users in a channel via a post containing a specially crafted payload that triggers catastrophic backtracking in the client-side markdown parser.. Mattermost Advisory ID: MMSA-2026-00658

Affected products

2
  • Mattermost/Mattermostllm-fuzzy2 versions
    <=11.7.2, <=11.6.4, <=10.11.19+ 1 more
    • (no CPE)range: <=11.7.2, <=11.6.4, <=10.11.19
    • cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*range: >=10.11.0,<10.11.20

Patches

Vulnerability mechanics

References

1

News mentions

0

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