{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-33868", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-03-24T15:10:05.678Z", "datePublished": "2026-03-27T19:50:07.687Z", "dateUpdated": "2026-03-31T18:54:24.919Z"}, "containers": {"cna": {"title": "Mastodon has a GET-Based Open Redirect via '/web/%2F<domain>'", "problemTypes": [{"descriptions": [{"cweId": "CWE-601", "lang": "en", "description": "CWE-601: URL Redirection to Untrusted Site ('Open Redirect')", "type": "CWE"}]}], "metrics": [{"cvssV3_1": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 4.3, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N", "version": "3.1"}}], "references": [{"name": "https://github.com/mastodon/mastodon/security/advisories/GHSA-xqw8-4j56-5hj6", "tags": ["x_refsource_CONFIRM"], "url": "https://github.com/mastodon/mastodon/security/advisories/GHSA-xqw8-4j56-5hj6"}], "affected": [{"vendor": "mastodon", "product": "mastodon", "versions": [{"version": ">= 4.5.0, < 4.5.8", "status": "affected"}, {"version": ">= 4.4.0, < 4.4.15", "status": "affected"}, {"version": "< 4.3.21", "status": "affected"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-03-27T19:50:07.687Z"}, "descriptions": [{"lang": "en", "value": "Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.5.8, 4.4.15, and 4.3.21, an unauthenticated Open Redirect vulnerability (CWE-601) exists in the `/web/*` route due to improper handling of URL-encoded path segments. An attacker can craft a specially encoded URL that causes the application to redirect users to an arbitrary external domain, enabling phishing attacks and potential OAuth credential theft. The issue occurs because URL-encoded slashes (`%2F`) bypass Rails path normalization and are interpreted as host-relative redirects. Versions 4.5.8, 4.4.15, and 4.3.21 patch the issue."}], "source": {"advisory": "GHSA-xqw8-4j56-5hj6", "discovery": "UNKNOWN"}}, "adp": [{"metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-03-31T18:50:44.597749Z", "id": "CVE-2026-33868", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-03-31T18:54:24.919Z"}}]}}

{"dataType": "CVE_RECORD", "containers": {"adp": [{"title": "CISA ADP Vulnrichment", "metrics": [{"other": {"type": "ssvc", "content": {"id": "CVE-2026-33868", "role": "CISA Coordinator", "options": [{"Exploitation": "none"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "version": "2.0.3", "timestamp": "2026-03-31T18:50:44.597749Z"}}}], "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-03-31T18:50:45.631Z"}}], "cna": {"title": "Mastodon has a GET-Based Open Redirect via '/web/%2F<domain>'", "source": {"advisory": "GHSA-xqw8-4j56-5hj6", "discovery": "UNKNOWN"}, "metrics": [{"cvssV3_1": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 4.3, "attackVector": "NETWORK", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N", "integrityImpact": "LOW", "userInteraction": "REQUIRED", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "NONE", "confidentialityImpact": "NONE"}}], "affected": [{"vendor": "mastodon", "product": "mastodon", "versions": [{"status": "affected", "version": ">= 4.5.0, < 4.5.8"}, {"status": "affected", "version": ">= 4.4.0, < 4.4.15"}, {"status": "affected", "version": "< 4.3.21"}]}], "references": [{"url": "https://github.com/mastodon/mastodon/security/advisories/GHSA-xqw8-4j56-5hj6", "name": "https://github.com/mastodon/mastodon/security/advisories/GHSA-xqw8-4j56-5hj6", "tags": ["x_refsource_CONFIRM"]}], "descriptions": [{"lang": "en", "value": "Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.5.8, 4.4.15, and 4.3.21, an unauthenticated Open Redirect vulnerability (CWE-601) exists in the `/web/*` route due to improper handling of URL-encoded path segments. An attacker can craft a specially encoded URL that causes the application to redirect users to an arbitrary external domain, enabling phishing attacks and potential OAuth credential theft. The issue occurs because URL-encoded slashes (`%2F`) bypass Rails path normalization and are interpreted as host-relative redirects. Versions 4.5.8, 4.4.15, and 4.3.21 patch the issue."}], "problemTypes": [{"descriptions": [{"lang": "en", "type": "CWE", "cweId": "CWE-601", "description": "CWE-601: URL Redirection to Untrusted Site ('Open Redirect')"}]}], "providerMetadata": {"orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-03-27T19:50:07.687Z"}}}, "cveMetadata": {"cveId": "CVE-2026-33868", "state": "PUBLISHED", "dateUpdated": "2026-03-31T18:54:24.919Z", "dateReserved": "2026-03-24T15:10:05.678Z", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "datePublished": "2026-03-27T19:50:07.687Z", "assignerShortName": "GitHub_M"}, "dataVersion": "5.2"}

{"configurations": [{"nodes": [{"cpeMatch": [{"criteria": "cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*", "matchCriteriaId": "91507204-15DF-4F1C-A1DC-59F0AD466214", "versionEndExcluding": "4.3.21", "vulnerable": true}, {"criteria": "cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*", "matchCriteriaId": "A37B2AD4-5027-464B-947A-63BDB06C33B8", "versionEndExcluding": "4.4.15", "versionStartIncluding": "4.4.0", "vulnerable": true}, {"criteria": "cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*", "matchCriteriaId": "BE32DA85-D71D-4CB8-8216-205780DBBB6A", "versionEndExcluding": "4.5.8", "versionStartIncluding": "4.5.0", "vulnerable": true}], "negate": false, "operator": "OR"}]}], "cveTags": [], "descriptions": [{"lang": "en", "value": "Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.5.8, 4.4.15, and 4.3.21, an unauthenticated Open Redirect vulnerability (CWE-601) exists in the `/web/*` route due to improper handling of URL-encoded path segments. An attacker can craft a specially encoded URL that causes the application to redirect users to an arbitrary external domain, enabling phishing attacks and potential OAuth credential theft. The issue occurs because URL-encoded slashes (`%2F`) bypass Rails path normalization and are interpreted as host-relative redirects. Versions 4.5.8, 4.4.15, and 4.3.21 patch the issue."}], "id": "CVE-2026-33868", "lastModified": "2026-03-30T19:14:17.297", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 4.3, "baseSeverity": "MEDIUM", "confidentialityImpact": "NONE", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "UNCHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 1.4, "source": "security-advisories@github.com", "type": "Secondary"}, {"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 6.1, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N", "version": "3.1"}, "exploitabilityScore": 2.8, "impactScore": 2.7, "source": "nvd@nist.gov", "type": "Primary"}]}, "published": "2026-03-27T20:16:34.333", "references": [{"source": "security-advisories@github.com", "tags": ["Vendor Advisory"], "url": "https://github.com/mastodon/mastodon/security/advisories/GHSA-xqw8-4j56-5hj6"}], "sourceIdentifier": "security-advisories@github.com", "vulnStatus": "Analyzed", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-601"}], "source": "security-advisories@github.com", "type": "Primary"}]}

{}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[4.5.0,4.5.8)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[4.4.0,4.4.15)"}}, {"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,4.3.21)"}}], "enrichment": {"confidence": 89.0, "confidence_source": "matching", "scores": [{"score": 89.0, "source": "matching"}]}, "original": {"product": "mastodon", "source": "cna", "vendor": "mastodon"}, "product": "mastodon", "vendor": "joinmastodon"}], "analysis": {"en": {"generated_at": "2026-03-30T21:06:56.315903+00:00", "value": {"mitigation_remediation": ["Upgrade Mastodon to a patched version (4.5.8 or later, 4.4.15 or later, or 4.3.21 or later)."], "summary": {"action": "Apply Patch", "impact": "Phishing and credential theft through open redirect"}, "threat_synthesis": {"affected_systems": "The issue exists in all Mastodon releases earlier than 4.5.8, 4.4.15, and 4.3.21. Unauthenticated attackers can target any instance running those older versions.", "description_and_impact": "The vulnerability is a GET-based open redirect in Mastodon\u2019s /web/* route. The application fails to normalize URL-encoded slashes, enabling an attacker to craft a URL that redirects a visitor to any external domain. This can be used to host phishing pages or force users to grant OAuth permissions to a malicious site.", "risk_and_exploitability": "The CVSS base score of 4.3 reflects moderate severity, and the EPSS score below 1% suggests a low likelihood of exploitation in the wild. The vulnerability is not listed in CISA\u2019s KEV catalog. Attack requires only a simple HTTP GET request and no credentials, so it can be triggered by anyone with internet access."}}}}, "created": "2026-03-29T20:30:20.903088+00:00", "updated": "2026-03-31T20:00:46.539765+00:00", "vendors": ["joinmastodon", "joinmastodon$PRODUCT$mastodon"]}