Skip to content
Fencer Intel
high 7.6

CVE-2026-62854 json

FreeScout: Stored XSS in mailbox signature via same-origin JS upload

published 3mo ago modified 23h ago also EUVD-2026-118363 , GHSA-jpq8-j69f-mj98

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository freescout-help-desk/freescout. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

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

  • freescout freescout 1.8.225

Is CVE-2026-62854 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
partial
Assessed
yesterday

Exploit prediction

0.22% chance of exploitation in the next 30 days, higher than 11% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-jpq8-j69f-mj98 referenced PoC, tagged "exploit" by a source, unverified

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

Sources

Fencer Intel 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.

The maintainers of freescout-help-desk/freescout published their own advisory on GitHub. Reviewed sources take precedence over it.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.