cvelistv5 - cve-2026-86349

CVE-2026-86349 (GCVE-0-2026-86349)

Vulnerability from cvelistv5

Published

2026-09-14 13:51

Modified

2026-09-14 19:23

Severity ?

4.3 (Medium) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

CWE

CWE-407 - Inefficient Algorithmic Complexity

Summary

Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.8, 10.11.x <= 10.11.22 fail to limit the nesting depth in the server-side Markdown parser which allows an authenticated attacker to cause a denial of service (CPU resource exhaustion) via a crafted post containing deeply nested blockquotes or list items.. Mattermost Advisory ID: MMSA-2026-00707

References

URL

Tags

https://mattermost.com/security-updates

vendor-advisory

Impacted products

	Vendor	Product	Version
	Mattermost	Mattermost	Version: 11.9.0 ≤ 11.9.0 Version: 11.8.0 ≤ 11.8.4 Version: 11.7.0 ≤ 11.7.8 Version: 10.11.0 ≤ 10.11.22

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-86349",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-14T19:13:43.392628Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-14T19:23:01.455Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Mattermost",
          "vendor": "Mattermost",
          "versions": [
            {
              "lessThanOrEqual": "11.9.0",
              "status": "affected",
              "version": "11.9.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "11.8.4",
              "status": "affected",
              "version": "11.8.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "11.7.8",
              "status": "affected",
              "version": "11.7.0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "10.11.22",
              "status": "affected",
              "version": "10.11.0",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "11.10.0"
            },
            {
              "status": "unaffected",
              "version": "11.9.1"
            },
            {
              "status": "unaffected",
              "version": "11.8.5"
            },
            {
              "status": "unaffected",
              "version": "11.7.9"
            },
            {
              "status": "unaffected",
              "version": "10.11.23"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "tr66net"
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Mattermost versions 11.9.x \u003c= 11.9.0, 11.8.x \u003c= 11.8.4, 11.7.x \u003c= 11.7.8, 10.11.x \u003c= 10.11.22 fail to limit the nesting depth in the server-side Markdown parser which allows an authenticated attacker to cause a denial of service (CPU resource exhaustion) via a crafted post containing deeply nested blockquotes or list items.. Mattermost Advisory ID: MMSA-2026-00707"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "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"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-407",
              "description": "CWE-407: Inefficient Algorithmic Complexity",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-14T13:51:30.175Z",
        "orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
        "shortName": "Mattermost"
      },
      "references": [
        {
          "name": "MMSA-2026-00707",
          "tags": [
            "vendor-advisory"
          ],
          "url": "https://mattermost.com/security-updates"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "Update Mattermost to versions 11.10.0, 11.9.1, 11.8.5, 11.7.9, 10.11.23 or higher."
        }
      ],
      "source": {
        "advisory": "MMSA-2026-00707",
        "defect": [
          "https://mattermost.atlassian.net/browse/MM-69398"
        ],
        "discovery": "EXTERNAL"
      },
      "title": "Mattermost Server Algorithmic DoS via Unbounded Markdown Block Nesting",
      "x_generator": {
        "engine": "cvelib 1.8.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
    "assignerShortName": "Mattermost",
    "cveId": "CVE-2026-86349",
    "datePublished": "2026-09-14T13:51:30.175Z",
    "dateReserved": "2026-09-07T09:38:22.768Z",
    "dateUpdated": "2026-09-14T19:23:01.455Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "vulnrichment": {
      "containers": "{\"cna\": {\"affected\": [{\"defaultStatus\": \"unaffected\", \"product\": \"Mattermost\", \"vendor\": \"Mattermost\", \"versions\": [{\"lessThanOrEqual\": \"11.9.0\", \"status\": \"affected\", \"version\": \"11.9.0\", \"versionType\": \"semver\"}, {\"lessThanOrEqual\": \"11.8.4\", \"status\": \"affected\", \"version\": \"11.8.0\", \"versionType\": \"semver\"}, {\"lessThanOrEqual\": \"11.7.8\", \"status\": \"affected\", \"version\": \"11.7.0\", \"versionType\": \"semver\"}, {\"lessThanOrEqual\": \"10.11.22\", \"status\": \"affected\", \"version\": \"10.11.0\", \"versionType\": \"semver\"}, {\"version\": \"11.10.0\", \"status\": \"unaffected\"}, {\"version\": \"11.9.1\", \"status\": \"unaffected\"}, {\"version\": \"11.8.5\", \"status\": \"unaffected\"}, {\"version\": \"11.7.9\", \"status\": \"unaffected\"}, {\"version\": \"10.11.23\", \"status\": \"unaffected\"}]}], \"credits\": [{\"lang\": \"en\", \"type\": \"finder\", \"value\": \"tr66net\"}], \"descriptions\": [{\"lang\": \"en\", \"value\": \"Mattermost versions 11.9.x \u003c= 11.9.0, 11.8.x \u003c= 11.8.4, 11.7.x \u003c= 11.7.8, 10.11.x \u003c= 10.11.22 fail to limit the nesting depth in the server-side Markdown parser which allows an authenticated attacker to cause a denial of service (CPU resource exhaustion) via a crafted post containing deeply nested blockquotes or list items.. Mattermost Advisory ID: MMSA-2026-00707\"}], \"metrics\": [{\"cvssV3_1\": {\"attackVector\": \"NETWORK\", \"attackComplexity\": \"LOW\", \"privilegesRequired\": \"LOW\", \"userInteraction\": \"NONE\", \"scope\": \"UNCHANGED\", \"confidentialityImpact\": \"NONE\", \"integrityImpact\": \"NONE\", \"availabilityImpact\": \"LOW\", \"version\": \"3.1\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L\", \"baseSeverity\": \"MEDIUM\", \"baseScore\": 4.3}, \"format\": \"CVSS\", \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"description\": \"CWE-407: Inefficient Algorithmic Complexity\", \"cweId\": \"CWE-407\"}]}], \"references\": [{\"url\": \"https://mattermost.com/security-updates\", \"name\": \"MMSA-2026-00707\", \"tags\": [\"vendor-advisory\"]}], \"solutions\": [{\"value\": \"Update Mattermost to versions 11.10.0, 11.9.1, 11.8.5, 11.7.9, 10.11.23 or higher.\", \"lang\": \"en\"}], \"source\": {\"advisory\": \"MMSA-2026-00707\", \"defect\": [\"https://mattermost.atlassian.net/browse/MM-69398\"], \"discovery\": \"EXTERNAL\"}, \"title\": \"Mattermost Server Algorithmic DoS via Unbounded Markdown Block Nesting\", \"providerMetadata\": {\"orgId\": \"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee\", \"shortName\": \"Mattermost\", \"dateUpdated\": \"2026-09-14T13:51:30.175Z\"}, \"x_generator\": {\"engine\": \"cvelib 1.8.0\"}}, \"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2026-86349\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2026-09-14T19:13:43.392628Z\"}}}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2026-09-14T19:15:30.809Z\"}}]}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-86349\", \"assignerOrgId\": \"9302f53e-dde5-4bf3-b2f2-a83f91ac0eee\", \"state\": \"PUBLISHED\", \"assignerShortName\": \"Mattermost\", \"dateReserved\": \"2026-09-07T09:38:22.768Z\", \"datePublished\": \"2026-09-14T13:51:30.175Z\", \"dateUpdated\": \"2026-09-14T19:23:01.455Z\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}

CERTFR-2026-AVI-1128

Vulnerability from certfr_avis

De multiples vulnérabilités ont été découvertes dans Mattermost Server. Elles permettent à un attaquant de provoquer un déni de service à distance.

Solutions

Se référer au bulletin de sécurité de l'éditeur pour l'obtention des correctifs (cf. section Documentation).

Impacted products

Vendor	Product	Description
Mattermost	Mattermost Server	Mattermost Server versions 11.8.x antérieures à 11.8.5
Mattermost	Mattermost Server	Mattermost Server versions 10.11.x antérieures à 10.11.23
Mattermost	Mattermost Server	Mattermost Server versions 11.7.x antérieures à 11.7.9
Mattermost	Mattermost Server	Mattermost Server versions 11.9.x antérieures à 11.9.1

References

Title

Publication Time

Tags

Bulletin de sécurité Mattermost MMSA-2026-00701	2026-09-07	vendor-advisory
Bulletin de sécurité Mattermost MMSA-2026-00707	2026-09-07	vendor-advisory

Show details on source website

JSON

To clipboard

{
  "$ref": "https://www.cert.ssi.gouv.fr/openapi.json",
  "affected_systems": [
    {
      "description": "Mattermost Server versions 11.8.x ant\u00e9rieures \u00e0 11.8.5",
      "product": {
        "name": "Mattermost Server",
        "vendor": {
          "name": "Mattermost",
          "scada": false
        }
      }
    },
    {
      "description": "Mattermost Server versions 10.11.x ant\u00e9rieures \u00e0 10.11.23",
      "product": {
        "name": "Mattermost Server",
        "vendor": {
          "name": "Mattermost",
          "scada": false
        }
      }
    },
    {
      "description": "Mattermost Server versions 11.7.x ant\u00e9rieures \u00e0 11.7.9",
      "product": {
        "name": "Mattermost Server",
        "vendor": {
          "name": "Mattermost",
          "scada": false
        }
      }
    },
    {
      "description": "Mattermost Server versions 11.9.x ant\u00e9rieures \u00e0 11.9.1",
      "product": {
        "name": "Mattermost Server",
        "vendor": {
          "name": "Mattermost",
          "scada": false
        }
      }
    }
  ],
  "affected_systems_content": "",
  "content": "## Solutions\n\nSe r\u00e9f\u00e9rer au bulletin de s\u00e9curit\u00e9 de l\u0027\u00e9diteur pour l\u0027obtention des correctifs (cf. section Documentation).",
  "cves": [
    {
      "name": "CVE-2026-86349",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-86349"
    },
    {
      "name": "CVE-2026-86348",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-86348"
    }
  ],
  "initial_release_date": "2026-09-08T00:00:00",
  "last_revision_date": "2026-09-15T00:00:00",
  "links": [],
  "reference": "CERTFR-2026-AVI-1128",
  "revisions": [
    {
      "description": "Version initiale",
      "revision_date": "2026-09-08T00:00:00.000000"
    },
    {
      "description": "Ajout des identifiants CVE, modification des risques en cons\u00e9quence.",
      "revision_date": "2026-09-15T00:00:00.000000"
    }
  ],
  "risks": [
    {
      "description": "D\u00e9ni de service \u00e0 distance"
    }
  ],
  "summary": "De multiples vuln\u00e9rabilit\u00e9s ont \u00e9t\u00e9 d\u00e9couvertes dans Mattermost Server. Elles permettent \u00e0 un attaquant de provoquer un d\u00e9ni de service \u00e0 distance.",
  "title": "Multiples vuln\u00e9rabilit\u00e9s dans Mattermost Server",
  "vendor_advisories": [
    {
      "published_at": "2026-09-07",
      "title": "Bulletin de s\u00e9curit\u00e9 Mattermost MMSA-2026-00701",
      "url": "https://mattermost.com/security-updates/"
    },
    {
      "published_at": "2026-09-07",
      "title": "Bulletin de s\u00e9curit\u00e9 Mattermost MMSA-2026-00707",
      "url": "https://mattermost.com/security-updates/"
    }
  ]
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
Confirmed: The vulnerability is confirmed from an analyst perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
Patched: This vulnerability was successfully patched by the user reporting the sighting.
Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
Not confirmed: The user expresses doubt about the veracity of the vulnerability.
Not patched: This vulnerability was not successfully patched by the user reporting the sighting.

Action not permitted

CVE-2026-86349 (GCVE-0-2026-86349)

Vulnerability from cvelistv5

CERTFR-2026-AVI-1128

Vulnerability from certfr_avis

Solutions

Tags

Sightings

Nomenclature