CVE-2026-62854 json
FreeScout: Stored XSS in mailbox signature via same-origin JS upload
published 2026-11-06 2 d ago modified 2026-11-06 2 d ago also EUVD-2026-118363
- cvss
- 7.6
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.2%
- EPSS 0.2% chance of exploitation in 30 days, percentile 11%
- public exploits
- 0
- none known
Summary
FreeScout is a self-hosted help desk and shared mailbox. Prior to 1.8.225, a user who can edit a mailbox signature can combine a scriptable file uploaded through /uploads/upload with nested tag fragments that bypass Helper::stripDangerousTags(). The resulting external script is served from the same origin, so the script-src 'self' policy permits it when another user opens the affected mailbox reply editor or new-ticket page. The script executes with the victim's FreeScout privileges and can read visible data and perform same-origin actions. This issue is fixed in version 1.8.225.
Patch / fix
Exploit prediction
0.21% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.6 | CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N |
Affected products
- freescout-help-desk freescout
Classification
- Weakness
-
- CWE-79 Improper Neutralization of Input During Web Page Generation
References
- github.com /freescout-help-desk/freescout/commit/315ad05f73886649cb8bc2c014dd74b62cc28502
- github.com /freescout-help-desk/freescout/commit/7f6a5042c1326ceaf511f13982178dce036cedbe
- github.com /freescout-help-desk/freescout/security/advisories/GHSA-jpq8-j69f-mj98
- github.com /freescout-help-desk/freescout/releases/tag/1.8.225
Sources
- CVE List CVE-2026-62854
- NVD CVE-2026-62854
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.