CVE-2026-126800
Hydro @hydrooj/ui-default before 4.59.1 Stored XSS via Markdown language- Class
Hydro @hydrooj/ui-default before 4.59.1 contains a stored cross-site scripting vulnerability that allows registered users to inject script by placing double quotes in language- class tokens within markdown-it-xss.ts. Attackers can store a payload in their profile bio that executes when administrators or other users view it, stealing the non-httpOnly sid session cookie for session hijacking.
Fixes and workarounds
Fix
The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.
Source: CNA: VulnCheckAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| @hydrooj/ui-default hydro-dev %40hydrooj/ui-default
npm |
≥ 0; < 4.59.1 (affected, semver)
Other versions: unaffected |
CNA: VulnCheck |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 4.0 / 9.3 critical |
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N | CNA: VulnCheck |
| 3.1 / 8.7 high |
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N | CNA: VulnCheck |
| 4.0 / 9.3 critical |
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/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 | NVD: [email protected] |
| 3.1 / 8.7 high |
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:N | NVD: [email protected] |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
- https://github.com/hydro-dev/Hydro/commit/3bae56fe8edddff12346bcb1c8281269c94688d8CNA: VulnCheck · patch
- https://github.com/hydro-dev/Hydro/blob/3c8286dd1350fcd00412e95d5b056dbfed64edda/packages/ui-default/backendlib/markdown-it-xss.ts#L150-L157CNA: VulnCheck · technical-description
- https://vul.yulun.ac.cn/20261107/hydro/CNA: VulnCheck · third-party-advisory
- https://www.vulncheck.com/advisories/hydro-hydrooj-ui-default-before-4.59.1-stored-xss-via-markdown-language-classCNA: VulnCheck · third-party-advisory
- https://github.com/hydro-dev/Hydro/blob/3c8286dd1350fcd00412e95d5b056dbfed64edda/packages/ui-default/backendlib/markdown-it-xss.ts#L150-L157[email protected]
- https://github.com/hydro-dev/Hydro/commit/3bae56fe8edddff12346bcb1c8281269c94688d8[email protected]
- https://vul.yulun.ac.cn/20261107/hydro/[email protected]
- https://www.vulncheck.com/advisories/hydro-hydrooj-ui-default-before-4.59.1-stored-xss-via-markdown-language-class[email protected]
For agents and automation
Read public disclosures for free as Markdown or JSON. Compatible browsers also expose native WebMCP tools to search disclosures, read this page, and discover API access.
Use the ontology-linked Cyber API with x402 pay per request, or a Y2 Pro or Elite API key with the intel:cyber scope.
Endpoints and access details
https://api.y2.dev/api/v2/cyber/cveshttps://api.y2.dev/api/v2/cyber/cves/{cveId}
A workspace owner or admin can create a Pro or Elite API key. Send Authorization: Bearer <Y2_API_KEY> from your trusted agent runtime.
For x402, omit Authorization and read the HTTP 402 payment challenge before signing a retry. Public browser tools do not make payments.