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CVE-2026-4915 Server panic via outgoing webhook responses

🗓️ 25 May 2026 07:10:23Reported by MattermostType 
cvelist
 cvelist
🔗 www.cve.org👁 60 Views

Mattermost server panics from outgoing webhook responses due to nil attachments not filtered, enabling authenticated denial of service.

Related
Affected
Refs
ReporterTitlePublishedViews
Family
attackerkb
attackerkb
CVE-2026-4915
25 May 202607:10
–attackerkb
bdu_fstec
BDU FSTEC
Mattermost DoS
1 Jun 202600:00
–bdu_fstec
cnnvd
CNNVD
Mattermost security vulnerabilities
25 May 202600:00
–cnnvd
cve
CVE
CVE-2026-4915
25 May 202607:10
–cve
euvd
EUVD
EUVD-2026-31646
25 May 202607:10
–euvd
github
Github Security Blog
Mattermost doesn't filter nil elements from outgoing webhook attachment payloads before processing
26 May 202613:30
–github
mend
Mend
CVE-2026-4915
25 May 202607:10
–mend
nvd
NVD
CVE-2026-4915
25 May 202608:16
–nvd
osv_cve
osv_cve
CVE-2026-4915 Server panic via outgoing webhook responses
25 May 202607:10
–osv_cve
osv_ghsa
osv_ghsa
GHSA-5GMF-X7HG-97WF Mattermost doesn't filter nil elements from outgoing webhook attachment payloads before processing
26 May 202613:30
–osv_ghsa
Rows per page
[
  {
    "defaultStatus": "unaffected",
    "product": "Mattermost",
    "vendor": "Mattermost",
    "versions": [
      {
        "lessThanOrEqual": "11.6.0",
        "status": "affected",
        "version": "11.6.0",
        "versionType": "semver"
      },
      {
        "lessThanOrEqual": "11.5.3",
        "status": "affected",
        "version": "11.5.0",
        "versionType": "semver"
      },
      {
        "lessThanOrEqual": "11.4.4",
        "status": "affected",
        "version": "11.4.0",
        "versionType": "semver"
      },
      {
        "lessThanOrEqual": "10.11.14",
        "status": "affected",
        "version": "10.11.0",
        "versionType": "semver"
      },
      {
        "version": "11.7.0",
        "status": "unaffected"
      },
      {
        "version": "11.6.1",
        "status": "unaffected"
      },
      {
        "version": "11.5.4",
        "status": "unaffected"
      },
      {
        "version": "11.4.5",
        "status": "unaffected"
      },
      {
        "version": "10.11.15",
        "status": "unaffected"
      }
    ]
  }
]

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