CVE-2026-42455 json
LinkWarden: Stored XSS via Client-Side Archive Upload (Unsanitized HTML served from same origin)
published 2026-05-08 6 mo ago modified 2026-07-24 3 mo ago also EUVD-2026-28872
- cvss
- 8.8
- version 4.0, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.5%
- EPSS 0.5% chance of exploitation in 30 days, percentile 39%
- public exploits
- 0
- none known
Summary
Linkwarden is a self-hosted, open-source collaborative bookmark manager to collect, organize and archive webpages. In versions 2.14.0 and prior, the archive upload endpoint (POST /api/v1/archives/[linkId]?format=4) accepts HTML files (text/html) without sanitizing JavaScript content. When the archive is later accessed via GET /api/v1/archives/[linkId]?format=4, the HTML is served with Content-Type: text/html from the Linkwarden origin, without any Content-Security-Policy header. This allows arbitrary JavaScript execution in the context of the authenticated Linkwarden sessio. At time of publication, there are no publicly available patches.
CISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- partial
- Assessed
- 5 mo ago
Exploit prediction
0.46% chance of exploitation in the next 30 days, higher than 39% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- github.com https://github.com/linkwarden/linkwarden/security/advisories/GHSA-fjvg-mch3-j3vg referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 8.8 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/VA:N/SC:N/SI:N/SA:N |
| CNA | 4.0 | 8.8 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:H/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 |
Affected products
- linkwarden linkwarden
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
Sources
- CVE List CVE-2026-42455
- NVD CVE-2026-42455
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.