CVE-2026-55617

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.

CVSS

No CVSS.

References

Link	Resource
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

Configurations

No configuration.

History

No history.

Information

Published : 2026-09-15 15:17

Updated : 2026-09-15 19:17

NVD link : CVE-2026-55617

Mitre link : CVE-2026-55617

CVE.ORG link : CVE-2026-55617

JSON object : View

Products Affected

No product.

CWE

CWE-613

Insufficient Session Expiration

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