SEPTEMBER 17, 2026
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Case File

CVE-2026-55617

MEDIUM · CVSS 6.9 EPSS 0.27% Public Exploit

Source: NVD + CISA KEV + EPSS · Published 2026-09-15 · Last synced 2026-09-17

CyberRota Analysis

AI-Generated

The session management logic in Hydro versions 4.10.4 to 5.0.2 allows an attacker to exploit stale session tokens, enabling account takeover and unauthorized access to sensitive data. This vulnerability poses a risk to any organization using affected versions of the Hydro online judge platform, particularly those handling sensitive user information. Users should prioritize upgrading to version 5.0.2 or later to mitigate this risk.

Public Exploit Signal

A public exploit, PoC, GitHub repository or Metasploit reference was detected for this CVE.

Detected Signals
exploit

Note: these links are listed for security research and verification purposes only.

CVE
CVE-2026-55617
Severity
MEDIUM
CVSS
6.9
EPSS
0.27%

Original NVD 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.