CVE-2026-96808 (GCVE-0-2026-96808)
Vulnerability from cvelistv5 – Published: 2026-09-23 16:58 – Updated: 2026-09-23 18:22
VLAI
EPSS
VEX
Summary
In Flatpak before 1.18.1, the revokefs writer, used by the flatpak-system-helper to receive repository data from unprivileged callers, validated file paths by rejecting literal .. components but did not prevent symlink traversal. A malicious local user in an active local session could obtain two revokefs sessions via the system helper, create a symlink in one session pointing into the other session's directory, and retain a file descriptor through that symlink. This allowed the attacker to modify files belonging to a different revokefs session after they had been validated and imported by the system helper. In particular, an attacker could use this to tamper with ostree commit objects in the system repository after they passed signature verification, enabling root-controlled file writes to attacker-chosen paths and local root privilege escalation.
Severity
7.4 (High)
SSVC
Exploitation: none
Automatable: no
Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-09-23 18:22 UTC
CWE
- CWE-61 - UNIX Symbolic Link (Symlink) Following
Assigner
References
1 reference
Impacted products
{
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-96808",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-09-23T18:22:36.969505Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-09-23T18:22:46.208Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"platforms": [
"Linux"
],
"product": "Flatpak",
"programFiles": [
"revokefs/writer.c"
],
"repo": "https://github.com/flatpak/flatpak",
"vendor": "Flatpak",
"versions": [
{
"lessThan": "1.18.1",
"status": "affected",
"version": "0",
"versionType": "semver"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:flatpak:flatpak:*:*:*:*:*:*:*:*",
"versionEndExcluding": "1.18.1",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In Flatpak before 1.18.1, the revokefs writer, used by the flatpak-system-helper to receive repository data from unprivileged callers, validated file paths by rejecting literal .. components but did not prevent symlink traversal. A malicious local user in an active local session could obtain two revokefs sessions via the system helper, create a symlink in one session pointing into the other session\u0027s directory, and retain a file descriptor through that symlink. This allowed the attacker to modify files belonging to a different revokefs session after they had been validated and imported by the system helper. In particular, an attacker could use this to tamper with ostree commit objects in the system repository after they passed signature verification, enabling root-controlled file writes to attacker-chosen paths and local root privilege escalation."
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "HIGH",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.4,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-61",
"description": "CWE-61 UNIX Symbolic Link (Symlink) Following",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-09-23T16:58:37.139Z",
"orgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
"shortName": "mitre"
},
"references": [
{
"url": "https://github.com/flatpak/flatpak/security/advisories/GHSA-qrwq-7qwx-q9rp"
}
],
"solutions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eFixed in 1.18.1 by commits:\u003c/p\u003e\n\u003cul\u003e\n\u003cli\u003e\u003ca target=\"_blank\" rel=\"noopener noreferrer\" href=\"https://github.com/flatpak/flatpak/commit/a3583bc87d4f86c2794ff879ea56fce95b0b0b5f\"\u003ea3583bc\u003c/a\u003e \"revokefs: Avoid symlink path traversal out of basefd in simple cases\"\u003c/li\u003e\n\u003cli\u003e\u003ca target=\"_blank\" rel=\"noopener noreferrer\" href=\"https://github.com/flatpak/flatpak/commit/b00c7b5073a25bdc34653642de543b5ef6fe0225\"\u003eb00c7b5\u003c/a\u003e \"revokefs: Avoid symlink path traversal in link(), rename()\"\u003c/li\u003e\n\u003cli\u003e\u003ca target=\"_blank\" rel=\"noopener noreferrer\" href=\"https://github.com/flatpak/flatpak/commit/4ddb5dc0de1bd25e52627f520a49063d94f79377\"\u003e4ddb5dc\u003c/a\u003e \"revokefs: Avoid symlink path traversal in symlink()\"\u003c/li\u003e\n\u003cli\u003e\u003ca target=\"_blank\" rel=\"noopener noreferrer\" href=\"https://github.com/flatpak/flatpak/commit/e7f96b4d1533f735ace2ea21dbf770e8d4be465a\"\u003ee7f96b4\u003c/a\u003e \"revokefs: Avoid symlink path traversal in chmod()\"\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eFor LTS operating system distributions, backports of these changes are available in the flatpak-1.16.x branch.\u003c/p\u003e"
}
],
"value": "Fixed in 1.18.1 by commits:\n\n\n\n * a3583bc https://github.com/flatpak/flatpak/commit/a3583bc87d4f86c2794ff879ea56fce95b0b0b5f \"revokefs: Avoid symlink path traversal out of basefd in simple cases\"\n\n * b00c7b5 https://github.com/flatpak/flatpak/commit/b00c7b5073a25bdc34653642de543b5ef6fe0225 \"revokefs: Avoid symlink path traversal in link(), rename()\"\n\n * 4ddb5dc https://github.com/flatpak/flatpak/commit/4ddb5dc0de1bd25e52627f520a49063d94f79377 \"revokefs: Avoid symlink path traversal in symlink()\"\n\n * e7f96b4 https://github.com/flatpak/flatpak/commit/e7f96b4d1533f735ace2ea21dbf770e8d4be465a \"revokefs: Avoid symlink path traversal in chmod()\"\n\n\n\n\nFor LTS operating system distributions, backports of these changes are available in the flatpak-1.16.x branch."
}
],
"x_generator": {
"engine": "CVE-Request-form 0.0.1"
}
}
},
"cveMetadata": {
"assignerOrgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
"assignerShortName": "mitre",
"cveId": "CVE-2026-96808",
"datePublished": "2026-09-23T16:58:37.139Z",
"dateReserved": "2026-09-23T16:58:36.801Z",
"dateUpdated": "2026-09-23T18:22:46.208Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2",
"vulnerability-lookup:meta": {
"epss": {
"cve": "CVE-2026-96808",
"date": "2026-09-24",
"epss": "0.00119",
"percentile": "0.01587"
},
"nvd": {
"cve": {
"affected": [
{
"affectedData": [
{
"defaultStatus": "unaffected",
"platforms": [
"Linux"
],
"product": "Flatpak",
"programFiles": [
"revokefs/writer.c"
],
"repo": "https://github.com/flatpak/flatpak",
"vendor": "Flatpak",
"versions": [
{
"lessThan": "1.18.1",
"status": "affected",
"version": "0",
"versionType": "semver"
}
]
}
],
"source": "cve@mitre.org"
}
],
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In Flatpak before 1.18.1, the revokefs writer, used by the flatpak-system-helper to receive repository data from unprivileged callers, validated file paths by rejecting literal .. components but did not prevent symlink traversal. A malicious local user in an active local session could obtain two revokefs sessions via the system helper, create a symlink in one session pointing into the other session\u0027s directory, and retain a file descriptor through that symlink. This allowed the attacker to modify files belonging to a different revokefs session after they had been validated and imported by the system helper. In particular, an attacker could use this to tamper with ostree commit objects in the system repository after they passed signature verification, enabling root-controlled file writes to attacker-chosen paths and local root privilege escalation."
}
],
"id": "CVE-2026-96808",
"lastModified": "2026-09-23T19:19:55.187",
"metrics": {
"cvssMetricV31": [
{
"cvssData": {
"attackComplexity": "HIGH",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.4,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.4,
"impactScore": 5.9,
"source": "cve@mitre.org",
"type": "Secondary"
}
],
"ssvcV203": [
{
"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"ssvcData": {
"id": "CVE-2026-96808",
"options": [
{
"exploitation": "none"
},
{
"automatable": "no"
},
{
"technicalImpact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-09-23T18:22:36.969505Z",
"version": "2.0.3"
}
}
]
},
"published": "2026-09-23T17:17:25.860",
"references": [
{
"source": "cve@mitre.org",
"url": "https://github.com/flatpak/flatpak/security/advisories/GHSA-qrwq-7qwx-q9rp"
}
],
"sourceIdentifier": "cve@mitre.org",
"vulnStatus": "Received",
"weaknesses": [
{
"description": [
{
"lang": "en",
"value": "CWE-61"
}
],
"source": "cve@mitre.org",
"type": "Secondary"
}
]
}
},
"redhat_vex": {
"aggregate_severity": "Important",
"current_release_date": "2026-09-23T18:31:35+00:00",
"cve": "CVE-2026-96808",
"id": "CVE-2026-96808",
"initial_release_date": "2026-09-23T16:58:37.139000+00:00",
"product_status:known_affected": "23",
"source": "Red Hat CSAF VEX",
"status": "final",
"title": "flatpak: Flatpak: Local privilege escalation via symlink traversal in revokefs writer",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-96808.json",
"version": "3"
},
"suse_vex": {
"aggregate_severity": "important",
"current_release_date": "2026-09-23T23:42:11Z",
"cve": "CVE-2026-96808",
"id": "CVE-2026-96808",
"initial_release_date": "2026-09-23T23:42:11Z",
"product_status:known_affected": "231",
"source": "SUSE CSAF VEX",
"status": "interim",
"title": "SUSE CVE CVE-2026-96808",
"url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-96808.json",
"version": "2"
},
"vulnrichment": {
"containers": {
"adp": [
{
"metrics": [
{
"other": {
"content": {
"id": "CVE-2026-96808",
"options": [
{
"Exploitation": "none"
},
{
"Automatable": "no"
},
{
"Technical Impact": "total"
}
],
"role": "CISA Coordinator",
"timestamp": "2026-09-23T18:22:36.969505Z",
"version": "2.0.3"
},
"type": "ssvc"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-09-23T18:22:41.941Z",
"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
"shortName": "CISA-ADP"
},
"title": "CISA ADP Vulnrichment"
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"platforms": [
"Linux"
],
"product": "Flatpak",
"programFiles": [
"revokefs/writer.c"
],
"repo": "https://github.com/flatpak/flatpak",
"vendor": "Flatpak",
"versions": [
{
"lessThan": "1.18.1",
"status": "affected",
"version": "0",
"versionType": "semver"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:a:flatpak:flatpak:*:*:*:*:*:*:*:*",
"versionEndExcluding": "1.18.1",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"descriptions": [
{
"lang": "en",
"value": "In Flatpak before 1.18.1, the revokefs writer, used by the flatpak-system-helper to receive repository data from unprivileged callers, validated file paths by rejecting literal .. components but did not prevent symlink traversal. A malicious local user in an active local session could obtain two revokefs sessions via the system helper, create a symlink in one session pointing into the other session\u0027s directory, and retain a file descriptor through that symlink. This allowed the attacker to modify files belonging to a different revokefs session after they had been validated and imported by the system helper. In particular, an attacker could use this to tamper with ostree commit objects in the system repository after they passed signature verification, enabling root-controlled file writes to attacker-chosen paths and local root privilege escalation."
}
],
"metrics": [
{
"cvssV3_1": {
"attackComplexity": "HIGH",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 7.4,
"baseSeverity": "HIGH",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"privilegesRequired": "NONE",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
},
"format": "CVSS",
"scenarios": [
{
"lang": "en",
"value": "GENERAL"
}
]
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-61",
"description": "CWE-61 UNIX Symbolic Link (Symlink) Following",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-09-23T16:58:37.139Z",
"orgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
"shortName": "mitre"
},
"references": [
{
"url": "https://github.com/flatpak/flatpak/security/advisories/GHSA-qrwq-7qwx-q9rp"
}
],
"solutions": [
{
"lang": "en",
"supportingMedia": [
{
"base64": false,
"type": "text/html",
"value": "\u003cp\u003eFixed in 1.18.1 by commits:\u003c/p\u003e\n\u003cul\u003e\n\u003cli\u003e\u003ca target=\"_blank\" rel=\"noopener noreferrer\" href=\"https://github.com/flatpak/flatpak/commit/a3583bc87d4f86c2794ff879ea56fce95b0b0b5f\"\u003ea3583bc\u003c/a\u003e \"revokefs: Avoid symlink path traversal out of basefd in simple cases\"\u003c/li\u003e\n\u003cli\u003e\u003ca target=\"_blank\" rel=\"noopener noreferrer\" href=\"https://github.com/flatpak/flatpak/commit/b00c7b5073a25bdc34653642de543b5ef6fe0225\"\u003eb00c7b5\u003c/a\u003e \"revokefs: Avoid symlink path traversal in link(), rename()\"\u003c/li\u003e\n\u003cli\u003e\u003ca target=\"_blank\" rel=\"noopener noreferrer\" href=\"https://github.com/flatpak/flatpak/commit/4ddb5dc0de1bd25e52627f520a49063d94f79377\"\u003e4ddb5dc\u003c/a\u003e \"revokefs: Avoid symlink path traversal in symlink()\"\u003c/li\u003e\n\u003cli\u003e\u003ca target=\"_blank\" rel=\"noopener noreferrer\" href=\"https://github.com/flatpak/flatpak/commit/e7f96b4d1533f735ace2ea21dbf770e8d4be465a\"\u003ee7f96b4\u003c/a\u003e \"revokefs: Avoid symlink path traversal in chmod()\"\u003c/li\u003e\n\u003c/ul\u003e\n\u003cp\u003eFor LTS operating system distributions, backports of these changes are available in the flatpak-1.16.x branch.\u003c/p\u003e"
}
],
"value": "Fixed in 1.18.1 by commits:\n\n\n\n * a3583bc https://github.com/flatpak/flatpak/commit/a3583bc87d4f86c2794ff879ea56fce95b0b0b5f \"revokefs: Avoid symlink path traversal out of basefd in simple cases\"\n\n * b00c7b5 https://github.com/flatpak/flatpak/commit/b00c7b5073a25bdc34653642de543b5ef6fe0225 \"revokefs: Avoid symlink path traversal in link(), rename()\"\n\n * 4ddb5dc https://github.com/flatpak/flatpak/commit/4ddb5dc0de1bd25e52627f520a49063d94f79377 \"revokefs: Avoid symlink path traversal in symlink()\"\n\n * e7f96b4 https://github.com/flatpak/flatpak/commit/e7f96b4d1533f735ace2ea21dbf770e8d4be465a \"revokefs: Avoid symlink path traversal in chmod()\"\n\n\n\n\nFor LTS operating system distributions, backports of these changes are available in the flatpak-1.16.x branch."
}
],
"x_generator": {
"engine": "CVE-Request-form 0.0.1"
}
}
},
"cveMetadata": {
"assignerOrgId": "8254265b-2729-46b6-b9e3-3dfca2d5bfca",
"assignerShortName": "mitre",
"cveId": "CVE-2026-96808",
"datePublished": "2026-09-23T16:58:37.139Z",
"dateReserved": "2026-09-23T16:58:36.801Z",
"dateUpdated": "2026-09-23T18:22:46.208Z",
"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…
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…