CVE-2026-2455 (GCVE-0-2026-2455)
Vulnerability from cvelistv5 – Published: 2026-03-16 14:53 – Updated: 2026-03-16 18:38
VLAI
EPSS
VEX
Title
SSRF bypass via IPv4-mapped IPv6 literals
Summary
Mattermost versions 11.3.x <= 11.3.0, 11.2.x <= 11.2.2, 10.11.x <= 10.11.10 fail to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation which allows an attacker to perform SSRF attacks against internal services via IPv4-mapped IPv6 literals (e.g., [::ffff:127.0.0.1]).. Mattermost Advisory ID: MMSA-2026-00585
Severity
4.3 (Medium)
SSVC
Exploitation: none
Automatable: no
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-03-16 18:37 UTC
CWE
- CWE-918 - Server-Side Request Forgery (SSRF)
Assigner
References
1 reference
| URL | Tags |
|---|---|
| https://mattermost.com/security-updates | vendor-advisory |
Impacted products
1 product
| Vendor | Product | Version | CPE status | |
|---|---|---|---|---|
| Mattermost | Mattermost |
Affected:
11.3.0 , ≤ 11.3.0
(semver)
Affected: 11.2.0 , ≤ 11.2.2 (semver) Affected: 10.11.0 , ≤ 10.11.10 (semver) Unaffected: 11.4.0 Unaffected: 11.3.1 Unaffected: 11.2.3 Unaffected: 10.11.11 |
guessed |
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-2455",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-03-16T18:37:36.914842Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-03-16T18:38:07.619Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Mattermost",
"vendor": "Mattermost",
"versions": [
{
"lessThanOrEqual": "11.3.0",
"status": "affected",
"version": "11.3.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "11.2.2",
"status": "affected",
"version": "11.2.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "10.11.10",
"status": "affected",
"version": "10.11.0",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "11.4.0"
},
{
"status": "unaffected",
"version": "11.3.1"
},
{
"status": "unaffected",
"version": "11.2.3"
},
{
"status": "unaffected",
"version": "10.11.11"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "winfunc"
}
],
"descriptions": [
{
"lang": "en",
"value": "Mattermost versions 11.3.x \u003c= 11.3.0, 11.2.x \u003c= 11.2.2, 10.11.x \u003c= 10.11.10 fail to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation which allows an attacker to perform SSRF attacks against internal services via IPv4-mapped IPv6 literals (e.g., [::ffff:127.0.0.1]).. Mattermost Advisory ID: MMSA-2026-00585"
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 4.3,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "LOW",
"integrityImpact": "NONE",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
"version": "3.1"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-918",
"description": "CWE-918: Server-Side Request Forgery (SSRF)",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-03-16T14:53:31.280Z",
"orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
"shortName": "Mattermost"
},
"references": [
{
"name": "MMSA-2026-00585",
"tags": [
"vendor-advisory"
],
"url": "https://mattermost.com/security-updates"
}
],
"solutions": [
{
"lang": "en",
"value": "Update Mattermost to versions 11.4.0, 11.3.1, 11.2.3, 10.11.11 or higher."
}
],
"source": {
"advisory": "MMSA-2026-00585",
"defect": [
"https://mattermost.atlassian.net/browse/MM-67262"
],
"discovery": "EXTERNAL"
},
"title": "SSRF bypass via IPv4-mapped IPv6 literals",
"x_generator": {
"engine": "cvelib 1.8.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
"assignerShortName": "Mattermost",
"cveId": "CVE-2026-2455",
"datePublished": "2026-03-16T14:53:31.280Z",
"dateReserved": "2026-02-13T10:45:36.473Z",
"dateUpdated": "2026-03-16T18:38:07.619Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-2455",
"date": "2026-09-20",
"epss": "0.00165",
"percentile": "0.06185"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"product": "Mattermost",
"vendor": "Mattermost",
"versions": [
{
"lessThanOrEqual": "11.3.0",
"status": "affected",
"version": "11.3.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "11.2.2",
"status": "affected",
"version": "11.2.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "10.11.10",
"status": "affected",
"version": "10.11.0",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "11.4.0"
},
{
"status": "unaffected",
"version": "11.3.1"
},
{
"status": "unaffected",
"version": "11.2.3"
},
{
"status": "unaffected",
"version": "10.11.11"
}
]
}
],
"source": "responsibledisclosure@mattermost.com"
}
],
"configurations": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
"matchCriteriaId": "B6E5F368-358C-429B-8F04-3C8DF4A71A91",
"versionEndExcluding": "10.11.11",
"versionStartIncluding": "10.11.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
"matchCriteriaId": "7F64C167-943D-4F3F-9374-BCC8DECB3881",
"versionEndExcluding": "11.2.3",
"versionStartIncluding": "11.2.0",
"vulnerable": true
},
{
"criteria": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
"matchCriteriaId": "945A6E29-209F-4992-8692-BEF63DCB6B98",
"versionEndExcluding": "11.3.1",
"versionStartIncluding": "11.3.0",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Mattermost versions 11.3.x \u003c= 11.3.0, 11.2.x \u003c= 11.2.2, 10.11.x \u003c= 10.11.10 fail to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation which allows an attacker to perform SSRF attacks against internal services via IPv4-mapped IPv6 literals (e.g., [::ffff:127.0.0.1]).. Mattermost Advisory ID: MMSA-2026-00585"
},
{
"lang": "es",
"value": "Las versiones de Mattermost 11.3.x \u0026lt;= 11.3.0, 11.2.x \u0026lt;= 11.2.2, 10.11.x \u0026lt;= 10.11.10 no logran canonicalizar las direcciones IPv6 mapeadas a IPv4 antes de la validaci\u00f3n de IP reservadas, lo que permite a un atacante realizar ataques SSRF contra servicios internos a trav\u00e9s de literales IPv6 mapeados a IPv4 (por ejemplo, [::ffff:127.0.0.1]).. ID de Aviso de Mattermost: MMSA-2026-00585"
}
],
"id": "CVE-2026-2455",
"lastModified": "2026-06-17T10:30:59.067",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 4.3,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "LOW",
"integrityImpact": "NONE",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
"version": "3.1"
},
"exploitabilityScore": 2.8,
"impactScore": 1.4,
"source": "responsibledisclosure@mattermost.com",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-2455",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-03-16T18:37:36.914842Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-03-16T15:16:22.277",
"references": [
{
"source": "responsibledisclosure@mattermost.com",
"tags": [
"Vendor Advisory"
],
"url": "https://mattermost.com/security-updates"
}
],
"sourceIdentifier": "responsibledisclosure@mattermost.com",
"vulnStatus": "Analyzed",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-918"
}
],
"source": "responsibledisclosure@mattermost.com",
"type": "Secondary"
}
]
}
},
"redhat_vex": {
"current_release_date": "2026-03-27T08:01:02+00:00",
"cve": "CVE-2026-2455",
"id": "CVE-2026-2455",
"initial_release_date": "2026-01-01T00:00:00+00:00",
"product_status:known_not_affected": "1",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "SSRF bypass via IPv4-mapped IPv6 literals",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-2455.json",
"version": "3"
},
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-2455",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "partial"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-03-16T18:37:36.914842Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-03-16T18:38:00.408Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Mattermost",
"vendor": "Mattermost",
"versions": [
{
"lessThanOrEqual": "11.3.0",
"status": "affected",
"version": "11.3.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "11.2.2",
"status": "affected",
"version": "11.2.0",
"versionType": "semver"
},
{
"lessThanOrEqual": "10.11.10",
"status": "affected",
"version": "10.11.0",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "11.4.0"
},
{
"status": "unaffected",
"version": "11.3.1"
},
{
"status": "unaffected",
"version": "11.2.3"
},
{
"status": "unaffected",
"version": "10.11.11"
}
]
}
],
"credits": [
{
"lang": "en",
"type": "finder",
"value": "winfunc"
}
],
"descriptions": [
{
"lang": "en",
"value": "Mattermost versions 11.3.x \u003c= 11.3.0, 11.2.x \u003c= 11.2.2, 10.11.x \u003c= 10.11.10 fail to canonicalize IPv4-mapped IPv6 addresses before reserved IP validation which allows an attacker to perform SSRF attacks against internal services via IPv4-mapped IPv6 literals (e.g., [::ffff:127.0.0.1]).. Mattermost Advisory ID: MMSA-2026-00585"
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "LOW",
"attackVector": "NETWORK",
"availabilityImpact": "NONE",
"baseScore": 4.3,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "LOW",
"integrityImpact": "NONE",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N",
"version": "3.1"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-918",
"description": "CWE-918: Server-Side Request Forgery (SSRF)",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-03-16T14:53:31.280Z",
"orgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
"shortName": "Mattermost"
},
"references": [
{
"name": "MMSA-2026-00585",
"tags": [
"vendor-advisory"
],
"url": "https://mattermost.com/security-updates"
}
],
"solutions": [
{
"lang": "en",
"value": "Update Mattermost to versions 11.4.0, 11.3.1, 11.2.3, 10.11.11 or higher."
}
],
"source": {
"advisory": "MMSA-2026-00585",
"defect": [
"https://mattermost.atlassian.net/browse/MM-67262"
],
"discovery": "EXTERNAL"
},
"title": "SSRF bypass via IPv4-mapped IPv6 literals",
"x_generator": {
"engine": "cvelib 1.8.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "9302f53e-dde5-4bf3-b2f2-a83f91ac0eee",
"assignerShortName": "Mattermost",
"cveId": "CVE-2026-2455",
"datePublished": "2026-03-16T14:53:31.280Z",
"dateReserved": "2026-02-13T10:45:36.473Z",
"dateUpdated": "2026-03-16T18:38:07.619Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
}
}
Loading…
Loading…
Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Loading…
The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Loading…
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
Loading…