CVE Explorer
CVE-2026-6339
Mattermost versions 11.5.x <= 11.5.1, 11.4.x <= 11.4.3 fail to validate the X-Requested-With header on the burn-on-read reveal endpoint which allows an authenticated channel member to force the reveal of a burn-on-read message without recipient consent via a crafted Markdown image tag.. Mattermost Advisory ID: MMSA-2026-00636
Known exploited
Not asserted
Disputed
No
Stale source
No
Conflicts
0
Affected products and versions
1 source assertion{"defaultStatus":"unaffected","product":"Mattermost","vendor":"Mattermost","versions":[{"lessThanOrEqual":"11.5.1","status":"affected","version":"11.5.0","versionType":"semver"},{"lessThanOrEqual":"11.4.3","status":"affected","version":"11.4.0","versionType":"semver"},{"status":"unaffected","version":"11.6.0"},{"status":"unaffected","version":"11.5.2"},{"status":"unaffected","version":"11.4.4"}]}
- cve_program_cvelist_v5affectedurn:baitaphish:normalized-source-record:v2:2603179b0e2bc767c90fd4d827e060f0d771996024861d15a785e9f063436e9c · sha256:308053a9c6c77d8e… · /containers/cna/affected/0
Provider-owned CVSS observations
1 source assertion{"metric":{"attackComplexity":"LOW","attackVector":"NETWORK","availabilityImpact":"LOW","baseScore":4.3,"baseSeverity":"MEDIUM","confidentialityImpact":"NONE","integrityImpact":"NONE","privilegesRequired":"LOW","scope":"UNCHANGED","userInteraction":"NONE","vectorString":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L","version":"3.1"},"metric_type":"cvssV3_1"}
- cve_program_cvelist_v5cvssurn:baitaphish:normalized-source-record:v2:2603179b0e2bc767c90fd4d827e060f0d771996024861d15a785e9f063436e9c · sha256:308053a9c6c77d8e… · /containers/cna/metrics/0/cvssV3_1
CWE assertions
1 source assertion{"cweId":"CWE-346","description":"CWE-346: Origin Validation Error","lang":"en","type":"CWE"}
- cve_program_cvelist_v5cweurn:baitaphish:normalized-source-record:v2:2603179b0e2bc767c90fd4d827e060f0d771996024861d15a785e9f063436e9c · sha256:308053a9c6c77d8e… · /containers/cna/problemTypes/0/descriptions/0
Source references
1 source assertion{"name":"MMSA-2026-00636","tags":["vendor-advisory"],"url":"https://mattermost.com/security-updates"}
- cve_program_cvelist_v5referenceurn:baitaphish:normalized-source-record:v2:2603179b0e2bc767c90fd4d827e060f0d771996024861d15a785e9f063436e9c · sha256:308053a9c6c77d8e… · /containers/cna/references/0
Attribution and limitations
- CVE Program CVEList V5: Reproduce the MITRE copyright designation and CVE license in copies. Source →
Provider severity values are preserved separately. Baitaphish does not convert them into a risk rating, infer affected products, or treat EPSS as observed exploitation.