### Impact
Using a carefully crafted request or malicious proxy, a user with `UserWrite` permissions could create another user with higher privileges than their own due to insufficient checks on the allowed set of permissions. The event would be captured in the Event Log.
### Patches
The issue has been fixed in 0.24.0 and 0.23.1.
### Workarounds
For users who are unable to upgrade, we recommend auditing users who have `UserWrite` permissions and regularly reviewing the Event Log for malicious activity.
### Kudos
Thank you to Michael Mazzolini (Ethical Hacker at WHO) for finding and disclosing this vulnerability.
{"id": "OSV:GHSA-5V95-V8C8-3RH6", "bulletinFamily": "software", "title": "Privilege escalation in rbac", "description": "### Impact\nUsing a carefully crafted request or malicious proxy, a user with `UserWrite` permissions could create another user with higher privileges than their own due to insufficient checks on the allowed set of permissions. The event would be captured in the Event Log.\n\n### Patches\nThe issue has been fixed in 0.24.0 and 0.23.1.\n\n### Workarounds\nFor users who are unable to upgrade, we recommend auditing users who have `UserWrite` permissions and regularly reviewing the Event Log for malicious activity.\n\n### Kudos\nThank you to Michael Mazzolini (Ethical Hacker at WHO) for finding and disclosing this vulnerability.", "published": "2021-05-21T14:32:55", "modified": "2021-05-20T22:26:21", "cvss": {"score": 6.5, "vector": "AV:N/AC:L/Au:S/C:P/I:P/A:P"}, "cvss2": {"acInsufInfo": false, "cvssV2": {"accessComplexity": "LOW", "accessVector": "NETWORK", "authentication": "SINGLE", "availabilityImpact": "PARTIAL", "baseScore": 6.5, "confidentialityImpact": "PARTIAL", "integrityImpact": "PARTIAL", "vectorString": "AV:N/AC:L/Au:S/C:P/I:P/A:P", "version": "2.0"}, "exploitabilityScore": 8.0, "impactScore": 6.4, "obtainAllPrivilege": false, "obtainOtherPrivilege": false, "obtainUserPrivilege": false, "severity": "MEDIUM", "userInteractionRequired": false}, "cvss3": {"cvssV3": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 8.8, "baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "UNCHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 5.9}, "href": "https://osv.dev/vulnerability/GHSA-5v95-v8c8-3rh6", "reporter": "Google", "references": ["https://github.com/google/exposure-notifications-verification-server/releases/tag/v0.24.0", "https://github.com/google/exposure-notifications-verification-server/commit/eb8cf40b12dbe79304f1133c06fb73419383cd95", "https://nvd.nist.gov/vuln/detail/CVE-2021-22538", "https://github.com/google/exposure-notifications-verification-server/security/advisories/GHSA-5v95-v8c8-3rh6", "https://github.com/google/exposure-notifications-verification-server/releases/tag/v0.23.1"], "cvelist": ["CVE-2021-22538"], "immutableFields": [], "type": "osv", "lastseen": "2022-05-12T01:14:03", "edition": 1, "viewCount": 2, "enchantments": {"affected_software": {"major_version": [{"name": "github.com/google/exposure-notifications-verification-server", "version": 0}]}, "backreferences": {"references": [{"idList": ["CVE-2021-22538"], "type": "cve"}, {"idList": ["GHSA-5V95-V8C8-3RH6"], "type": "github"}]}, "dependencies": {"references": [{"idList": ["CVE-2021-22538"], "type": "cve"}, {"idList": ["GHSA-5V95-V8C8-3RH6"], "type": "github"}]}, "score": {"value": 2.3, "vector": "NONE"}, "epss": [{"cve": "CVE-2021-22538", "epss": "0.001270000", "percentile": "0.456420000", "modified": "2023-03-20"}], "vulnersScore": 2.3}, "_state": {"dependencies": 1659964613, "score": 1684016453, "affected_software_major_version": 1666695388, "epss": 1679326080}, "_internal": {"score_hash": "a564aced98b53c5854ee89215105b1e9"}, "affectedSoftware": [{"name": "github.com/google/exposure-notifications-verification-server", "operator": "lt", "version": "0.23.1"}]}
{"cve": [{"lastseen": "2023-05-27T14:23:11", "description": "A privilege escalation vulnerability impacting the Google Exposure Notification Verification Server (versions prior to 0.23.1), allows an attacker who (1) has UserWrite permissions and (2) is using a carefully crafted request or malicious proxy, to create another user with higher privileges than their own. This occurs due to insufficient checks on the allowed set of permissions. The new user creation event would be captured in the Event Log.", "cvss3": {"exploitabilityScore": 2.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "baseScore": 8.8, "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1", "userInteraction": "NONE"}, "impactScore": 5.9}, "published": "2021-03-31T21:15:00", "type": "cve", "title": "CVE-2021-22538", "cwe": ["CWE-276"], "bulletinFamily": "NVD", "cvss2": {"severity": "MEDIUM", "exploitabilityScore": 8.0, "obtainAllPrivilege": false, "userInteractionRequired": false, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "LOW", "confidentialityImpact": "PARTIAL", "availabilityImpact": "PARTIAL", "integrityImpact": "PARTIAL", "baseScore": 6.5, "vectorString": "AV:N/AC:L/Au:S/C:P/I:P/A:P", "version": "2.0", "accessVector": "NETWORK", "authentication": "SINGLE"}, "impactScore": 6.4, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2021-22538"], "modified": "2021-04-06T14:11:00", "cpe": [], "id": "CVE-2021-22538", "href": "https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-22538", "cvss": {"score": 6.5, "vector": "AV:N/AC:L/Au:S/C:P/I:P/A:P"}, "cpe23": []}], "github": [{"lastseen": "2023-05-27T15:15:54", "description": "### Impact\nUsing a carefully crafted request or malicious proxy, a user with `UserWrite` permissions could create another user with higher privileges than their own due to insufficient checks on the allowed set of permissions. The event would be captured in the Event Log.\n\n### Patches\nThe issue has been fixed in 0.24.0 and 0.23.1.\n\n### Workarounds\nFor users who are unable to upgrade, we recommend auditing users who have `UserWrite` permissions and regularly reviewing the Event Log for malicious activity.\n\n### Kudos\nThank you to Michael Mazzolini (Ethical Hacker at WHO) for finding and disclosing this vulnerability.", "cvss3": {"exploitabilityScore": 2.8, "cvssV3": {"baseSeverity": "HIGH", "confidentialityImpact": "HIGH", "attackComplexity": "LOW", "scope": "UNCHANGED", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "baseScore": 8.8, "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "version": "3.1", "userInteraction": "NONE"}, "impactScore": 5.9}, "published": "2021-05-21T14:32:55", "type": "github", "title": "Privilege escalation in rbac", "bulletinFamily": "software", "cvss2": {"severity": "MEDIUM", "exploitabilityScore": 8.0, "obtainAllPrivilege": false, "userInteractionRequired": false, "obtainOtherPrivilege": false, "cvssV2": {"accessComplexity": "LOW", "confidentialityImpact": "PARTIAL", "availabilityImpact": "PARTIAL", "integrityImpact": "PARTIAL", "baseScore": 6.5, "vectorString": "AV:N/AC:L/Au:S/C:P/I:P/A:P", "version": "2.0", "accessVector": "NETWORK", "authentication": "SINGLE"}, "impactScore": 6.4, "acInsufInfo": false, "obtainUserPrivilege": false}, "cvelist": ["CVE-2021-22538"], "modified": "2023-02-01T05:05:46", "id": "GHSA-5V95-V8C8-3RH6", "href": "https://github.com/advisories/GHSA-5v95-v8c8-3rh6", "cvss": {"score": 6.5, "vector": "AV:N/AC:L/Au:S/C:P/I:P/A:P"}}]}