{"id":"CVE-2026-35594","revision":null,"records":[{"revision":"7b1e2e1958494a6ca2e52958edc1239e","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-35594","aliases":[],"title":"Vikunja Link Share JWT tokens remain valid for 72 hours after share deletion or permission downgrade","description":"Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, Vikunja's link share authentication (GetLinkShareFromClaims in pkg/models/link_sharing.go) constructs authorization objects entirely from JWT claims without any server-side database validation. When a project owner deletes a link share or downgrades its permissions, all previously issued JWTs continue to grant the original permission level for up to 72 hours (the default service.jwtttl). This vulnerability is fixed in 2.3.0.","state":0,"publishedAt":"2026-04-10T15:55:04.929+00:00","modifiedAt":"2026-04-14T14:32:15.339+00:00","affected":[{"ecosystem":"Vendor product","name":"vikunja","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"go-vikunja\",\n                    \"product\": \"vikunja\",\n                    \"versions\": [\n                        {\n                            \"version\": \"< 2.3.0\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","score":6.5,"severity":"MEDIUM"}],"references":["https://github.com/go-vikunja/vikunja/security/advisories/GHSA-96q5-xm3p-7m84","https://github.com/go-vikunja/vikunja/pull/2581","https://github.com/go-vikunja/vikunja/commit/379d8a5c19334ffe4846003f590e202c31a75479","https://github.com/go-vikunja/vikunja/releases/tag/v2.3.0"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-35594","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-35594","identifiers":["CVE-2026-35594"]},"retained":false,"historicalAffected":[]},{"revision":"f1387027a5f34d9f870dc6821bab13a3","observedAt":"2026-10-28T04:56:14.31+00:00","statement":{"source":"euvd","id":"EUVD-2026-21417","aliases":["CVE-2026-35594","GHSA-96q5-xm3p-7m84"],"title":"Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, Vikunja's link share authentication (GetLinkShareFromClaims in pkg/models/link_sharing.go) constructs authorization objects entirely from JWT claims without any…","description":"Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, Vikunja's link share authentication (GetLinkShareFromClaims in pkg/models/link_sharing.go) constructs authorization objects entirely from JWT claims without any server-side database validation. When a project owner deletes a link share or downgrades its permissions, all previously issued JWTs continue to grant the original permission level for up to 72 hours (the default service.jwtttl). This vulnerability is fixed in 2.3.0.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","score":6.5,"severity":null}],"references":["https://github.com/go-vikunja/vikunja/security/advisories/GHSA-96q5-xm3p-7m84","https://github.com/go-vikunja/vikunja/pull/2581","https://github.com/go-vikunja/vikunja/commit/379d8a5c19334ffe4846003f590e202c31a75479","https://github.com/go-vikunja/vikunja/releases/tag/v2.3.0"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-21417","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Apr 10, 2026, 3:55:04 PM","dateUpdated":"Apr 14, 2026, 2:32:15 PM"},"relatedAdvisories":[],"note":"EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON."},"key":"euvd:EUVD-2026-21417","identifiers":["EUVD-2026-21417","CVE-2026-35594","GHSA-96q5-xm3p-7m84"]},"retained":false,"historicalAffected":[]},{"revision":"3036aeae82bd4b03b53c3a585f2e7867","observedAt":"2026-10-27T09:03:12.132+00:00","statement":{"source":"nvd","id":"CVE-2026-35594","aliases":[],"title":"Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, Vikunja's link share authentication (GetLinkShareFromClaims in pkg/models/link_sharing.go) constructs authorization objects entirely from JWT claims without any…","description":"Vikunja is an open-source self-hosted task management platform. Prior to 2.3.0, Vikunja's link share authentication (GetLinkShareFromClaims in pkg/models/link_sharing.go) constructs authorization objects entirely from JWT claims without any server-side database validation. When a project owner deletes a link share or downgrades its permissions, all previously issued JWTs continue to grant the original permission level for up to 72 hours (the default service.jwtttl). This vulnerability is fixed in 2.3.0.","state":0,"publishedAt":"2026-04-10T16:16:32+00:00","modifiedAt":"2026-10-26T21:10:00.17+00:00","affected":[],"metrics":[{"system":"CVSS 3.1 · security-advisories@github.com · Secondary","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","score":6.5,"severity":"MEDIUM"}],"references":["https://github.com/go-vikunja/vikunja/commit/379d8a5c19334ffe4846003f590e202c31a75479","https://github.com/go-vikunja/vikunja/pull/2581","https://github.com/go-vikunja/vikunja/releases/tag/v2.3.0","https://github.com/go-vikunja/vikunja/security/advisories/GHSA-96q5-xm3p-7m84"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-35594","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Analyzed","weaknesses":["CWE-613"],"productCriteria":["cpe:2.3:a:vikunja:vikunja:*:*:*:*:*:*:*:*"],"sourceDates":{"published":"2026-04-10T16:16:32.000","lastModified":"2026-10-26T21:10:00.170"},"relatedAdvisories":[],"note":"NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON."},"key":"nvd:CVE-2026-35594","identifiers":["CVE-2026-35594"]},"retained":false,"historicalAffected":[]},{"revision":"c0a355b91d6749b3ac35a97a049d3ce1","observedAt":"2026-10-24T13:19:41.952+00:00","statement":{"source":"osv","id":"GHSA-96q5-xm3p-7m84","aliases":["CVE-2026-35594","GO-2026-5276"],"title":"Vikunja: Link Share JWT tokens remain valid for 72 hours after share deletion or permission downgrade","description":"## Title\nLink Share JWT tokens remain valid for 72 hours after share deletion or permission downgrade\n\n## Description\n\nVikunja's link share authentication constructs authorization objects entirely from JWT claims without any server-side database validation. When a project owner deletes a link share or downgrades its permissions, all previously issued JWTs continue to grant the **original** permission level for up to **72 hours** (the default `service.jwtttl`).\n\n`GetLinkShareFromClaims` at `pkg/models/link_sharing.go` lines 88-119 performs **zero database queries** — it builds the `LinkSharing` struct purely from JWT claim values (`id`, `hash`, `project_id`, `permission`, `sharedByID`). This struct is passed directly to permission checks:\n\n| Function | File | Lines | DB queries |\n|----------|------|-------|------------|\n| `GetLinkShareFromClaims` | `link_sharing.go` | 88-119 | 0 |\n| `Project.CanRead` (link share) | `project_permissions.go` | 105-108 | 0 |\n| `Project.CanWrite` (link share) | `project_permissions.go` | 50-53 | 0 |\n| `Project.IsAdmin` (link share) | `project_permissions.go` | 192-194 | 0 |\n\n**Contrast with user tokens:** User JWTs use a 10-minute TTL (`ServiceJWTTTLShort`) with `sid` claim and server-side sessions enabling revocation. Link share JWTs use a 72-hour TTL (`ServiceJWTTTL`) with no `sid`, no server-side session, and no refresh mechanism.\n\n**Permalink:**\n- `GetLinkShareFromClaims`: `pkg/models/link_sharing.go:88-119`\n- `NewLinkShareJWTAuthtoken`: `pkg/modules/auth/auth.go:141-160`\n- Permission checks: `pkg/models/project_permissions.go:50-53, 105-108, 192-194`\n- TTL defaults: `pkg/config/config.go:337-339`\n\n### PoC\n\n```bash\n# 1. Create an Admin-level link share on project 42\ncurl -X PUT \"https://vikunja.example.com/api/v1/projects/42/shares\" \\\n  -H \"Authorization: Bearer <owner-jwt>\" \\\n  -H \"Content-Type: application/json\" \\\n  -d '{\"permission\": 2}'\n# Response: {\"id\": 5, \"hash\": \"abc123\", ...}\n\n# 2. Obtain link share JWT (72h TTL, no sid claim)\ncurl -X POST \"https://vikunja.example.com/api/v1/shares/abc123/auth\"\n# Response: {\"token\": \"<link-share-jwt>\"}\n\n# 3. Delete the link share\ncurl -X DELETE \"https://vikunja.example.com/api/v1/projects/42/shares/5\" \\\n  -H \"Authorization: Bearer <owner-jwt>\"\n# 200 OK — share row removed from database\n\n# 4. Use the deleted share's JWT — STILL WORKS for up to 72 hours\ncurl -X GET \"https://vikunja.example.com/api/v1/projects/42/tasks\" \\\n  -H \"Authorization: Bearer <link-share-jwt>\"\n# 200 OK — full task list returned with Admin permissions\n\n# 5. Permission downgrade variant:\n# Delete Admin share → create Read-only share → old JWT still has Admin access\n```\n\n### Impact\n\n- Revoked link shares remain functional for up to 72 hours (default TTL)\n- Project owners cannot respond to security events (leaked URLs, access revocation) in real time\n- Permission downgrades have no effect on outstanding tokens\n- Scope: single project per token, severity scales with permission level (Admin > Write > Read)\n\n### Fix\n\nAdd database validation in `GetLinkShareFromClaims`:\n\n```go\nfunc GetLinkShareFromClaims(claims jwt.MapClaims) (share *LinkSharing, err error) {\n    id, is := claims[\"id\"].(float64)\n    if !is {\n        return nil, &ErrLinkShareTokenInvalid{}\n    }\n    // Validate against database\n    s := db.NewSession()\n    defer s.Close()\n    share, err = GetLinkShareByID(s, int64(id))\n    if err != nil {\n        return nil, err  // Share was deleted\n    }\n    // Verify permission not downgraded\n    claimedPermission := Permission(claims[\"permission\"].(float64))\n    if share.Permission < claimedPermission {\n        return nil, &ErrLinkShareTokenInvalid{}\n    }\n    return share, nil\n}\n```\n\nAlternatives: shorter TTL with refresh mechanism, token blocklist, or session tracking matching user token pattern.","state":0,"publishedAt":"2026-04-10T15:31:11+00:00","modifiedAt":"2026-07-21T13:55:25+00:00","affected":[{"ecosystem":"Go","name":"code.vikunja.io/api","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"2.3.0"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V3","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/go-vikunja/vikunja/security/advisories/GHSA-96q5-xm3p-7m84","https://nvd.nist.gov/vuln/detail/CVE-2026-35594","https://github.com/go-vikunja/vikunja/pull/2581","https://github.com/go-vikunja/vikunja/commit/379d8a5c19334ffe4846003f590e202c31a75479","https://github.com/go-vikunja/vikunja","https://github.com/go-vikunja/vikunja/releases/tag/v2.3.0"],"sourceUrl":"https://github.com/advisories/GHSA-96q5-xm3p-7m84","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-96q5-xm3p-7m84","identifiers":["GHSA-96q5-xm3p-7m84","CVE-2026-35594","GO-2026-5276"]},"retained":false,"historicalAffected":[]},{"revision":"c43b094c62bd4b6eb7e050b6d73a3196","observedAt":"2026-10-24T13:19:41.952+00:00","statement":{"source":"osv","id":"GO-2026-5276","aliases":["CVE-2026-35594","GHSA-96q5-xm3p-7m84"],"title":"Vikunja: Link Share JWT tokens remain valid for 72 hours after share deletion or permission downgrade in code.vikunja.io/api","description":"Vikunja: Link Share JWT tokens remain valid for 72 hours after share deletion or permission downgrade in code.vikunja.io/api.\n\nNOTE: The source advisory for this report contains additional versions that could not be automatically mapped to standard Go module versions.\n\n(If this is causing false-positive reports from vulnerability scanners, please suggest an edit to the report.)\n\nThe additional affected modules and versions are: code.vikunja.io/api before v2.3.0.","state":0,"publishedAt":"2026-06-25T18:43:15+00:00","modifiedAt":"2026-06-25T19:45:23.2393445+00:00","affected":[{"ecosystem":"Go","name":"code.vikunja.io/api","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"0"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[],"references":["https://github.com/go-vikunja/vikunja/security/advisories/GHSA-96q5-xm3p-7m84","https://nvd.nist.gov/vuln/detail/CVE-2026-35594","https://github.com/go-vikunja/vikunja/commit/379d8a5c19334ffe4846003f590e202c31a75479","https://github.com/go-vikunja/vikunja/pull/2581","https://github.com/go-vikunja/vikunja/releases/tag/v2.3.0"],"sourceUrl":"https://osv.dev/vulnerability/GO-2026-5276","license":"OSV · upstream source license applies","key":"osv:GO-2026-5276","identifiers":["GO-2026-5276","CVE-2026-35594","GHSA-96q5-xm3p-7m84"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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