CVE-2026-55617: Hydro Insufficient Session Expiration When Recreating Vulnerability

Q: What is CVE-2026-55617?

CVE-2026-55617 is a security vulnerability in Hydro involving Insufficient session expiration when recreating sessions under CWE-613: Insufficient Session Expiration.

Q: Which Hydro versions are affected?

Affected versions include releases prior to 5.0.2 across affected packages: hydrooj.

Q: What version fixes CVE-2026-55617?

Upgrading to 5.0.2 (or the latest patched release for your respective branch) resolves the vulnerability.

Q: Is hydrooj affected?

Yes, hydrooj is affected in releases prior to 5.0.2. Upgrade your dependency to 5.0.2 or later.

Q: What CWE is associated with CVE-2026-55617?

CVE-2026-55617 is classified under CWE-613: Insufficient Session Expiration (According to WASC, "Insufficient Session Expiration is when a web site permits an attacker to reuse old session credentials or session IDs for authorization.").

Q: How can I check npm dependencies for CVE-2026-55617?

Run the dependency tree command: 'npm ls hydrooj'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.

MODERATE

Advisory Identifier: GHSA-94jp-7776-qj6q

CWE-613

Published 2026-06-18

Advisory Summary

CVE-2026-55617 is a MODERATE insufficient session expiration when recreating vulnerability (CWE-613: Insufficient Session Expiration) affecting Hydro libraries in the npm ecosystem. The issue involves insufficient session expiration when recreating sessions. Remediation is available by upgrading affected packages to version 5.0.2.

CVE-2026-55617 at a Glance

CVE Identifier CVE-2026-55617

GHSA Identifier GHSA-94jp-7776-qj6q

Severity MODERATE

CVSS v3.1 Base Score N/A

CWE Classification CWE-613: Insufficient Session Expiration

Affected Product Hydro

Package Ecosystem npm

Published Date 2026-06-18

Last Updated 2026-06-18

How to Fix CVE-2026-55617

To remediate this vulnerability, upgrade all affected Hydro dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

hydrooj fixed: 5.0.2

npm install hydrooj@5.0.2

Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release:

npm ls hydrooj

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-55617, inspect your project dependencies using npm:

npm ls hydrooj

Analyze the terminal output to locate any version of Hydro in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 5.0.2), your application is affected.

Note: The npm ls hydrooj command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-613: Insufficient Session Expiration, where according to wasc, "insufficient session expiration is when a web site permits an attacker to reuse old session credentials or session ids for authorization.". In Hydro, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

### Impact Hydro 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. As 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. The 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. Successful 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. ### Patches The issue has been patched by deleting the old server-side session token before creating a new one during session recreation. Patched in: - Pull request: https://github.com/hydro-dev/Hydro/pull/1173 - Patch commit: https://github.com/hydro-dev/Hydro/commit/8450390fcce5f7dc3f11c43a14f1d76dbb949a0d - Merge commit: https://github.com/hydro-dev/Hydro/commit/8d76be8f0b83d911bf7671962b0467e9d4b5719a Users should upgrade to a version containing this patch. ### Workarounds If 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. Administrators 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.

CVE-2026-55617 Affected Hydro Versions

1 component(s)

Fixed Versions:

5.0.2

Product / Package	Ecosystem	Affected Versions	Fixed Version
hydrooj npm/hydrooj	npm	≥ 4.10.4 < 5.0.2	5.0.2

References

GitHub Advisory / Wiki ADVISORY

https://github.com/hydro-dev/Hydro/security/advisories/GHSA-94jp-7776-qj6q

Hydro Source Repository REPOSITORY

https://github.com/hydro-dev/Hydro/pull/1173

Security Fix Commit FIX COMMIT

https://github.com/hydro-dev/Hydro/commit/8450390fcce5f7dc3f11c43a14f1d76dbb949a0d

Security Fix Commit FIX COMMIT

https://github.com/hydro-dev/Hydro/commit/8d76be8f0b83d911bf7671962b0467e9d4b5719a

Hydro Source Repository REPOSITORY

https://github.com/hydro-dev/Hydro

Frequently Asked Questions

What is CVE-2026-55617?

CVE-2026-55617 is a security vulnerability in Hydro involving Insufficient session expiration when recreating sessions under CWE-613: Insufficient Session Expiration.

Which Hydro versions are affected?

Affected versions include releases prior to 5.0.2 across affected packages: hydrooj.

What version fixes CVE-2026-55617?

Upgrading to 5.0.2 (or the latest patched release for your respective branch) resolves the vulnerability.

Is hydrooj affected?

Yes, hydrooj is affected in releases prior to 5.0.2. Upgrade your dependency to 5.0.2 or later.

What CWE is associated with CVE-2026-55617?

CVE-2026-55617 is classified under CWE-613: Insufficient Session Expiration (According to WASC, "Insufficient Session Expiration is when a web site permits an attacker to reuse old session credentials or session IDs for authorization.").

How can I check npm dependencies for CVE-2026-55617?

Run the dependency tree command: 'npm ls hydrooj'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.

Machine-readable OSV JSON OSV v1.5 Schema

Normalized schema output

View Raw JSON

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-94jp-7776-qj6q",
  "modified" : "2026-06-18T13:06:35Z",
  "published" : "2026-06-18T13:06:35Z",
  "aliases" : [ "CVE-2026-55617" ],
  "summary" : "Hydro: Insufficient session expiration when recreating sessions",
  "details" : "### 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.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "hydrooj"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "4.10.4"
      }, {
        "fixed" : "5.0.2"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 5.0.1"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/hydro-dev/Hydro/security/advisories/GHSA-94jp-7776-qj6q"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/hydro-dev/Hydro/pull/1173"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/hydro-dev/Hydro/commit/8450390fcce5f7dc3f11c43a14f1d76dbb949a0d"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/hydro-dev/Hydro/commit/8d76be8f0b83d911bf7671962b0467e9d4b5719a"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/hydro-dev/Hydro"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-613" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-18T13:06:35Z",
    "nvd_published_at" : null
  }
}

CVSS V4

N/A MODERATE

Attack Vector N/A

Attack Complexity N/A

Privileges Required N/A

User Interaction N/A

Scope N/A

Confidentiality N/A

Integrity N/A

Availability N/A

Vector String

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

Advisory Metadata

Source ID: GHSA-94jp-7776-qj6q
Schema Version: 1.4.0
Published: 2026-06-18 13:06
Last Modified: 2026-06-18 13:06
Database Record File: advisories/github-reviewed/2026/06/GHSA-94jp-7776-qj6q/GHSA-94jp-7776-qj6q.json