{"id":"CVE-2026-55617","revision":null,"records":[{"revision":"807ee62842eb42b6b1760fae6bc6fd6f","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-55617","aliases":[],"title":"Hydro: Insufficient session expiration when recreating sessions","description":"Hydro is a next-generation high-performance online judge platform. From 4.10.4 until 5.0.2, the session recreation logic in packages/hydrooj/src/service/layers/base.ts creates a replacement session token without deleting the previous token from the server-side session token store, so an old sid cookie can remain valid after logout or another renewal flow. An attacker who possesses a victim's previously valid stale cookie can replay it over HTTP or HTTPS without knowing the victim's username or password and without victim interaction at exploitation time. Successful replay can take over the victim's account, disclose private data, and permit unauthorized modification or deletion of data available to that account. This issue is fixed in version 5.0.2.","state":0,"publishedAt":"2026-09-15T14:45:11.664+00:00","modifiedAt":"2026-09-15T18:02:57.088+00:00","affected":[{"ecosystem":"Vendor product","name":"Hydro","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"hydro-dev\",\n                    \"product\": \"Hydro\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 4.10.4, < 5.0.2\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N","score":6.9,"severity":"MEDIUM"}],"references":["https://github.com/hydro-dev/Hydro/security/advisories/GHSA-94jp-7776-qj6q","https://github.com/hydro-dev/Hydro/pull/1173","https://github.com/hydro-dev/Hydro/commit/8450390fcce5f7dc3f11c43a14f1d76dbb949a0d","https://github.com/hydro-dev/Hydro/commit/8d76be8f0b83d911bf7671962b0467e9d4b5719a"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-55617","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-55617","identifiers":["CVE-2026-55617"]},"retained":false,"historicalAffected":[]},{"revision":"e7244660b8384ba6a29417eff75e3363","observedAt":"2026-11-11T14:03:20.553+00:00","statement":{"source":"euvd","id":"EUVD-2026-78768","aliases":["CVE-2026-55617","GHSA-94jp-7776-qj6q"],"title":"Hydro is a next-generation high-performance online judge platform. From 4.10.4 until 5.0.2, the session recreation logic in packages/hydrooj/src/service/layers/base.ts creates a replacement session token without deleting the previous token …","description":"Hydro is a next-generation high-performance online judge platform. From 4.10.4 until 5.0.2, the session recreation logic in packages/hydrooj/src/service/layers/base.ts creates a replacement session token without deleting the previous token from the server-side session token store, so an old sid cookie can remain valid after logout or another renewal flow. An attacker who possesses a victim's previously valid stale cookie can replay it over HTTP or HTTPS without knowing the victim's username or password and without victim interaction at exploitation time. Successful replay can take over the victim's account, disclose private data, and permit unauthorized modification or deletion of data available to that account. This issue is fixed in version 5.0.2.","state":0,"publishedAt":null,"modifiedAt":null,"affected":[],"metrics":[{"system":"EUVD CVSS 4.0","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N","score":6.9,"severity":null}],"references":["https://github.com/hydro-dev/Hydro/security/advisories/GHSA-94jp-7776-qj6q","https://github.com/hydro-dev/Hydro/pull/1173","https://github.com/hydro-dev/Hydro/commit/8450390fcce5f7dc3f11c43a14f1d76dbb949a0d","https://github.com/hydro-dev/Hydro/commit/8d76be8f0b83d911bf7671962b0467e9d4b5719a"],"sourceUrl":"https://euvd.enisa.europa.eu/vulnerability/EUVD-2026-78768","license":"ENISA EUVD · source terms and attribution apply","enrichment":{"sourceStatus":null,"weaknesses":[],"productCriteria":[],"sourceDates":{"datePublished":"Sep 15, 2026, 2:45:11 PM","dateUpdated":"Sep 15, 2026, 6:02:57 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-2026-78768","identifiers":["EUVD-2026-78768","CVE-2026-55617","GHSA-94jp-7776-qj6q"]},"retained":false,"historicalAffected":[]},{"revision":"956a6f8273b14cfab87389446e87bd8a","observedAt":"2026-10-25T14:19:05.298+00:00","statement":{"source":"nvd","id":"CVE-2026-55617","aliases":[],"title":"Hydro is a next-generation high-performance online judge platform. From 4.10.4 until 5.0.2, the session recreation logic in packages/hydrooj/src/service/layers/base.ts creates a replacement session token without deleting the previous token …","description":"Hydro is a next-generation high-performance online judge platform. From 4.10.4 until 5.0.2, the session recreation logic in packages/hydrooj/src/service/layers/base.ts creates a replacement session token without deleting the previous token from the server-side session token store, so an old sid cookie can remain valid after logout or another renewal flow. An attacker who possesses a victim's previously valid stale cookie can replay it over HTTP or HTTPS without knowing the victim's username or password and without victim interaction at exploitation time. Successful replay can take over the victim's account, disclose private data, and permit unauthorized modification or deletion of data available to that account. This issue is fixed in version 5.0.2.","state":0,"publishedAt":"2026-09-15T15:17:18.93+00:00","modifiedAt":"2026-09-30T17:51:56.193+00:00","affected":[],"metrics":[{"system":"CVSS 4.0 · security-advisories@github.com · Secondary","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:N/VA:N/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","score":6.9,"severity":"MEDIUM"}],"references":["https://github.com/hydro-dev/Hydro/commit/8450390fcce5f7dc3f11c43a14f1d76dbb949a0d","https://github.com/hydro-dev/Hydro/commit/8d76be8f0b83d911bf7671962b0467e9d4b5719a","https://github.com/hydro-dev/Hydro/pull/1173","https://github.com/hydro-dev/Hydro/security/advisories/GHSA-94jp-7776-qj6q"],"sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-55617","license":"NIST NVD usage terms; underlying source attribution retained","enrichment":{"sourceStatus":"Deferred","weaknesses":["CWE-613"],"productCriteria":[],"sourceDates":{"published":"2026-09-15T15:17:18.930","lastModified":"2026-09-30T17:51:56.193"},"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-2026-55617","identifiers":["CVE-2026-55617"]},"retained":false,"historicalAffected":[]},{"revision":"b231bfd0df5c41458cda1b58fc95ba91","observedAt":"2026-10-24T13:17:17.793+00:00","statement":{"source":"osv","id":"GHSA-94jp-7776-qj6q","aliases":["CVE-2026-55617"],"title":"Hydro: Insufficient session expiration when recreating sessions","description":"### Impact\n\nHydro contains an insufficient session expiration vulnerability in its session recreation logic. When a session is recreated, including during logout or other session renewal flows, Hydro creates a new session token but does not delete the previous server-side session token.\n\nAs a result, an old sid cookie may remain valid even after the legitimate user logs out or the session is recreated. An attacker who has obtained a victim's previous sid cookie can replay that cookie over HTTP or HTTPS and continue to access the affected Hydro instance as the victim.\n\nThe attacker does not need the victim's username or password. Exploitation requires possession of a previously valid stale sid cookie, but no user interaction is required at exploitation time.\n\nSuccessful exploitation may allow account takeover within the affected Hydro instance. For a normal user account, this may allow disclosure of private data and unauthorized modification or deletion of data available to the victim.\n\n### Patches\n\nThe issue has been patched by deleting the old server-side session token before creating a new one during session recreation.\n\nPatched in:\n\n- Pull request: https://github.com/hydro-dev/Hydro/pull/1173\n- Patch commit: https://github.com/hydro-dev/Hydro/commit/8450390fcce5f7dc3f11c43a14f1d76dbb949a0d\n- Merge commit: https://github.com/hydro-dev/Hydro/commit/8d76be8f0b83d911bf7671962b0467e9d4b5719a\n\nUsers should upgrade to a version containing this patch.\n\n### Workarounds\n\nIf upgrading immediately is not possible, administrators should reduce the risk by forcing all existing sessions to expire or by clearing the server-side session token store after applying a local patch.\n\nAdministrators should also review logs for suspicious use of stale sid cookies and rotate any exposed session cookies. However, these mitigations do not fully fix the vulnerability. The recommended remediation is to upgrade to a patched version.","state":0,"publishedAt":"2026-06-18T13:06:35+00:00","modifiedAt":"2026-06-18T13:26:30.193032+00:00","affected":[{"ecosystem":"npm","name":"hydrooj","ranges":[{"type":"SEMVER","events":[{"kind":"introduced","version":"4.10.4"},{"kind":"fixed","version":"5.0.2"}]}],"versions":[],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V4","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"MODERATE"}],"references":["https://github.com/hydro-dev/Hydro/security/advisories/GHSA-94jp-7776-qj6q","https://github.com/hydro-dev/Hydro/pull/1173","https://github.com/hydro-dev/Hydro/commit/8450390fcce5f7dc3f11c43a14f1d76dbb949a0d","https://github.com/hydro-dev/Hydro/commit/8d76be8f0b83d911bf7671962b0467e9d4b5719a","https://github.com/hydro-dev/Hydro"],"sourceUrl":"https://github.com/advisories/GHSA-94jp-7776-qj6q","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-94jp-7776-qj6q","identifiers":["GHSA-94jp-7776-qj6q","CVE-2026-55617"]},"retained":false,"historicalAffected":[]}],"coverage":[{"source":"cisa-kev:global","scope":"Complete CISA KEV catalog; all vendors. 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