{"id":"CVE-2026-62367","aliases":["EUVD-2026-95993","GHSA-xv7q-fvmc-jx96","GO-2026-6758"],"status":"published","title":"Vikunja: OIDC email-fallback account linking ignores email_verified, enabling local-account takeover","description":"Vikunja is an open-source self-hosted task management platform. In versions 1.0.0 through 2.3.0, when an administrator enables the per-provider `emailfallback` option on an OpenID Connect provider, Vikunja links an SSO login to a pre-existing local (username+password) account using only the `email` claim from the IdP. The fallback never checks an `email_verified` (or Microsoft `xms_edov`) signal and never requires the matched account's password. An attacker who can obtain a token from the configured issuer carrying a victim's email logs in as that victim with a full session, with no consent or interaction from the victim. Version 2.4.0 fixes the issue.","severity":{"version":"4.0","score":7.5,"vector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-09","score":0.00089,"percentile":0.00381,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":true,"fix_available":true},"cwes":["CWE-287","CWE-290","CWE-345"],"published":"2026-10-09T20:49:06Z","modified":"2026-10-28T02:31:05Z","exploits":[{"source":"pocgithub","id":"federiconbaez/cortex9-vikunja-oidc-email-verified-linking-model","title":"federiconbaez/cortex9-vikunja-oidc-email-verified-linking-model","date":"2026-11-09","url":"https://github.com/federiconbaez/cortex9-vikunja-oidc-email-verified-linking-model"}],"fixes":[{"ecosystem":"Go","package":"code.vikunja.io/api","fixed_in":["2.4.0"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"Go","package":"code.vikunja.io/api","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"1.0.0"},{"last_affected":"2.3.0"},{"fixed":"2.4.0"}]}]},{"source":"osv","ecosystem":"Go","package":"code.vikunja.io/api","ranges":[{"type":"SEMVER","events":[{"introduced":"1.0.0"},{"fixed":"2.4.0"}]}]},{"source":"osv","ecosystem":"Go","package":"code.vikunja.io/api","ranges":[{"type":"SEMVER","events":[{"introduced":"0"}]}]}],"products":[{"vendor":"go-vikunja","product":"vikunja"}],"references":[{"url":"https://github.com/go-vikunja/vikunja/security/advisories/GHSA-xv7q-fvmc-jx96","tags":["x_refsource_CONFIRM","advisory","web"]},{"url":"https://github.com/go-vikunja/vikunja/commit/7854f2729ab72000210b61c25929678fd6901630","tags":["x_refsource_MISC","fix","web"]},{"url":"https://github.com/go-vikunja/vikunja/releases/tag/v2.4.0","tags":["x_refsource_MISC","web"]},{"url":"https://github.com/advisories/GHSA-xv7q-fvmc-jx96"},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/62xxx/CVE-2026-62367.json","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-62367","tags":["advisory"]},{"url":"https://github.com/go-vikunja/vikunja","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2026-62367","title":"Vikunja: OIDC email-fallback account linking ignores email_verified, enabling local-account takeover","description":"Vikunja is an open-source self-hosted task management platform. In versions 1.0.0 through 2.3.0, when an administrator enables the per-provider `emailfallback` option on an OpenID Connect provider, Vikunja links an SSO login to a pre-existing local (username+password) account using only the `email` claim from the IdP. The fallback never checks an `email_verified` (or Microsoft `xms_edov`) signal and never requires the matched account's password. An attacker who can obtain a token from the configured issuer carrying a victim's email logs in as that victim with a full session, with no consent or interaction from the victim. Version 2.4.0 fixes the issue.","status":"published","published":"2026-10-09T20:49:08.891Z","modified":"2026-10-13T20:25:26.027Z","cvss":[{"version":"4.0","score":7.5,"vector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high","assessor":"cna"}],"cwes":["CWE-287","CWE-290","CWE-345"],"updated_at":"2026-11-02T14:20:14.665567Z"}],"euvd":[{"id":"EUVD-2026-95993","description":"Vikunja is an open-source self-hosted task management platform. In versions 1.0.0 through 2.3.0, when an administrator enables the per-provider `emailfallback` option on an OpenID Connect provider, Vikunja links an SSO login to a pre-existing local (username+password) account using only the `email` claim from the IdP. The fallback never checks an `email_verified` (or Microsoft `xms_edov`) signal and never requires the matched account's password. An attacker who can obtain a token from the configured issuer carrying a victim's email logs in as that victim with a full session, with no consent or interaction from the victim. Version 2.4.0 fixes the issue.","status":"published","published":"2026-10-09T20:49:08Z","modified":"2026-10-13T20:25:26Z","cvss":[{"version":"4.0","score":7.5,"vector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high"}],"updated_at":"2026-11-02T17:27:18.393051Z"}],"ghsa":[{"id":"GHSA-xv7q-fvmc-jx96","title":"Vikunja: OIDC email-fallback account linking ignores email_verified, enabling local-account takeover","description":"## Summary\n\nWith the per-provider OIDC `emailfallback` option enabled, Vikunja links an SSO login to a pre-existing **local** (username+password) account using only the `email` claim — no `email_verified` (or Microsoft `xms_edov`) check and no password check, on the unauthenticated callback. An attacker who can make the configured issuer emit a token bearing a victim's email logs in as that victim with a full session and no victim interaction (the nOAuth / Grafana CVE-2023-3128 class). The 2.3.0 fix for GHSA-8jvc-mcx6-r4cg added a TOTP gate, not an `email_verified` gate, so users without TOTP remain exposed.\n\n## Details\n\nReferences are `pkg/modules/auth/openid/openid.go` at HEAD. Identity is first resolved on the immutable `(issuer, subject)` pair (`openid.go:428`). On a subject miss with `emailfallback` on, `fallbackSearchUsers` adds an email-only lookup against local accounts:\n\n```go\n// openid.go:413\nsearches = append(searches, \u0026user.User{Issuer: user.IssuerLocal, Email: cl.Email})\n```\n\n`getUser` resolves this via `s.Get()`, which ANDs non-zero fields -\u003e `WHERE issuer='local' AND email=?`. Local users always have `Issuer=\"local\"` (`user_create.go:38`), so the lookup matches any local account by email alone; `getOrCreateUser` returns it and the caller mints a session — the password is never read. The `claims` struct has no `email_verified` field (`openid.go:80`) and `getClaims` never consults one; a repo-wide grep for `email_verified`/`xms_edov` returns nothing. The code already warns about this at `openid.go:388` (\"Discouraged for untrusted providers where someone can set email without verification\") — but enforces nothing.\n\n## Impact\n\nUnauthenticated takeover of any existing **local** account (read/write/delete its projects, tasks, attachments, shares), bypassing the password. Scope notes: only `issuer='local'` accounts are matched (not pure-SSO users); the attacker's `sub` is not bound to the victim record, but the attack is repeatable; TOTP users are protected by the 2.3.0 `enforceTOTPIfRequired` gate (`openid.go:250`), non-TOTP users are not.\n\n## Preconditions\n\n1. Admin enabled `emailfallback: true` (defaults false — a default install is unaffected).\n2. The configured issuer lets the attacker assert the victim's unverified email: a self-service IdP (Keycloak/Authentik/Auth0/Dex with editable email), a mixed federation, or a multi-tenant Entra `/common` app. `iss`/`aud` are pinned, but the attacker controls `email`, not the issuer.\n3. The victim has a local account.\n\nNot reachable against a single-tenant IdP that verifies email and disallows self-set addresses.\n\n## Recommended Fix\n\nAdd `email_verified` to the `claims` struct and require it `true` on the email-fallback branch before linking to a local account; reject when absent/false. For Entra also require `xms_edov` and pin multi-tenant configs to an allowed-tenant list. Fail closed on an email collision not backed by a verified email from a trusted single-tenant issuer rather than silently logging the caller in.","status":"published","published":"2026-10-09T20:49:06Z","modified":"2026-10-09T20:49:07Z","cvss":[{"version":"4.0","score":7.5,"vector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-287","CWE-290","CWE-345"],"updated_at":"2026-11-02T14:41:31.175024Z"}],"nvd":[{"id":"CVE-2026-62367","description":"Vikunja is an open-source self-hosted task management platform. In versions 1.0.0 through 2.3.0, when an administrator enables the per-provider `emailfallback` option on an OpenID Connect provider, Vikunja links an SSO login to a pre-existing local (username+password) account using only the `email` claim from the IdP. The fallback never checks an `email_verified` (or Microsoft `xms_edov`) signal and never requires the matched account's password. An attacker who can obtain a token from the configured issuer carrying a victim's email logs in as that victim with a full session, with no consent or interaction from the victim. Version 2.4.0 fixes the issue.","status":"published","published":"2026-10-09T21:17:05.47Z","modified":"2026-10-16T20:04:29.76Z","cvss":[{"version":"4.0","score":7.5,"vector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"}],"cwes":["CWE-287","CWE-290","CWE-345"],"updated_at":"2026-11-02T14:12:55.473789Z"}],"osv":[{"id":"CVE-2026-62367","title":"Vikunja: OIDC email-fallback account linking ignores email_verified, enabling local-account takeover","description":"Vikunja is an open-source self-hosted task management platform. In versions 1.0.0 through 2.3.0, when an administrator enables the per-provider `emailfallback` option on an OpenID Connect provider, Vikunja links an SSO login to a pre-existing local (username+password) account using only the `email` claim from the IdP. The fallback never checks an `email_verified` (or Microsoft `xms_edov`) signal and never requires the matched account's password. An attacker who can obtain a token from the configured issuer carrying a victim's email logs in as that victim with a full session, with no consent or interaction from the victim. Version 2.4.0 fixes the issue.","status":"published","published":"2026-10-09T20:49:08.891Z","modified":"2026-10-28T02:31:05.35854425Z","cvss":[{"version":"4.0","score":7.5,"vector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-287","CWE-290","CWE-345"],"updated_at":"2026-11-02T15:45:13.306117Z"},{"id":"GHSA-xv7q-fvmc-jx96","title":"Vikunja: OIDC email-fallback account linking ignores email_verified, enabling local-account takeover","description":"## Summary\n\nWith the per-provider OIDC `emailfallback` option enabled, Vikunja links an SSO login to a pre-existing **local** (username+password) account using only the `email` claim — no `email_verified` (or Microsoft `xms_edov`) check and no password check, on the unauthenticated callback. An attacker who can make the configured issuer emit a token bearing a victim's email logs in as that victim with a full session and no victim interaction (the nOAuth / Grafana CVE-2023-3128 class). The 2.3.0 fix for GHSA-8jvc-mcx6-r4cg added a TOTP gate, not an `email_verified` gate, so users without TOTP remain exposed.\n\n## Details\n\nReferences are `pkg/modules/auth/openid/openid.go` at HEAD. Identity is first resolved on the immutable `(issuer, subject)` pair (`openid.go:428`). On a subject miss with `emailfallback` on, `fallbackSearchUsers` adds an email-only lookup against local accounts:\n\n```go\n// openid.go:413\nsearches = append(searches, \u0026user.User{Issuer: user.IssuerLocal, Email: cl.Email})\n```\n\n`getUser` resolves this via `s.Get()`, which ANDs non-zero fields -\u003e `WHERE issuer='local' AND email=?`. Local users always have `Issuer=\"local\"` (`user_create.go:38`), so the lookup matches any local account by email alone; `getOrCreateUser` returns it and the caller mints a session — the password is never read. The `claims` struct has no `email_verified` field (`openid.go:80`) and `getClaims` never consults one; a repo-wide grep for `email_verified`/`xms_edov` returns nothing. The code already warns about this at `openid.go:388` (\"Discouraged for untrusted providers where someone can set email without verification\") — but enforces nothing.\n\n## Impact\n\nUnauthenticated takeover of any existing **local** account (read/write/delete its projects, tasks, attachments, shares), bypassing the password. Scope notes: only `issuer='local'` accounts are matched (not pure-SSO users); the attacker's `sub` is not bound to the victim record, but the attack is repeatable; TOTP users are protected by the 2.3.0 `enforceTOTPIfRequired` gate (`openid.go:250`), non-TOTP users are not.\n\n## Preconditions\n\n1. Admin enabled `emailfallback: true` (defaults false — a default install is unaffected).\n2. The configured issuer lets the attacker assert the victim's unverified email: a self-service IdP (Keycloak/Authentik/Auth0/Dex with editable email), a mixed federation, or a multi-tenant Entra `/common` app. `iss`/`aud` are pinned, but the attacker controls `email`, not the issuer.\n3. The victim has a local account.\n\nNot reachable against a single-tenant IdP that verifies email and disallows self-set addresses.\n\n## Recommended Fix\n\nAdd `email_verified` to the `claims` struct and require it `true` on the email-fallback branch before linking to a local account; reject when absent/false. For Entra also require `xms_edov` and pin multi-tenant configs to an allowed-tenant list. Fail closed on an email collision not backed by a verified email from a trusted single-tenant issuer rather than silently logging the caller in.","status":"published","published":"2026-10-09T20:49:06Z","modified":"2026-10-19T21:40:54.288683723Z","cvss":[{"version":"4.0","score":7.5,"vector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","level":"high"}],"cwes":["CWE-287","CWE-290","CWE-345"],"updated_at":"2026-11-02T15:47:00.604718Z"},{"id":"GO-2026-6758","title":"Vikunja: OIDC email-fallback account linking ignores email_verified, enabling local-account takeover in code.vikunja.io/api","description":"Vikunja: OIDC email-fallback account linking ignores email_verified, enabling local-account takeover 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 from v1.0.0 before v2.4.0.","status":"published","published":"2026-10-19T21:08:26Z","modified":"2026-10-19T21:31:49.973995144Z","updated_at":"2026-11-02T15:47:03.11707Z"}]}}