# CVE-2026-62854: FreeScout: Stored XSS in mailbox signature via same-origin JS upload

Status: published. Published: 2026-11-06. Updated: 2026-11-11.

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.

## Remediation

- fix: FreeScout: GitHub reports patched versions 1.8.226. Check the advisory for the affected release branch. (source: GitHub GHSA-jpq8-j69f-mj98) — https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-jpq8-j69f-mj98

## Affected products and versions

- freescout-help-desk / freescout: < 1.8.225 (affected). Source: CNA: GitHub_M
-  / FreeScout (FreeScout): <1.8.226 (affected, GitHub advisory range). Source: GitHub GHSA-jpq8-j69f-mj98

## Severity and prioritization

- CVSS 3.1: 7.6 (high); CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N; source: CNA: GitHub_M

- CVSS 3.1: 7.6 (high); CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:L/A:N; source: NVD: security-advisories@github.com

- CISA KEV: No listing in collected sources

- EPSS: 0.21% as of 2026-11-10; percentile 11.90%

- SSVC: exploitation poc; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-79

## Exploit evidence

- exploit: https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-jpq8-j69f-mj98 (ADP: CISA-ADP)

## References

- https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-jpq8-j69f-mj98 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/freescout-help-desk/freescout/commit/315ad05f73886649cb8bc2c014dd74b62cc28502 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/freescout-help-desk/freescout/commit/7f6a5042c1326ceaf511f13982178dce036cedbe (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/freescout-help-desk/freescout/releases/tag/1.8.225 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-jpq8-j69f-mj98 (ADP: CISA-ADP; exploit)

- https://github.com/freescout-help-desk/freescout/commit/315ad05f73886649cb8bc2c014dd74b62cc28502 (security-advisories@github.com)

- https://github.com/freescout-help-desk/freescout/commit/7f6a5042c1326ceaf511f13982178dce036cedbe (security-advisories@github.com)

- https://github.com/freescout-help-desk/freescout/releases/tag/1.8.225 (security-advisories@github.com)

- https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-jpq8-j69f-mj98 (security-advisories@github.com)

- https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-jpq8-j69f-mj98 (GitHub Security Advisories; advisory)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-62854; retrieved 2026-11-11; source updated 2026-11-11

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-62854; retrieved 2026-11-06; source updated 2026-11-06

- GitHub Security Advisories: https://github.com/freescout-help-desk/freescout/security/advisories/GHSA-jpq8-j69f-mj98; retrieved 2026-11-08; source updated 2026-07-15

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-62854; retrieved 2026-11-11; source updated Not reported

Revision: 947fa96bfd3e5f0fa3f38eb7f8d4ec87b6cc4646981672824f69528da1abf801

Canonical: https://y2.dev/cve/CVE-2026-62854

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