# CVE-2026-117535: REDAXO before 5.21.3 Reflected XSS via opener_link in Media Pool

Status: published. Published: 2026-10-27. Updated: 2026-11-02.

REDAXO before 5.21.3 contains a reflected cross-site scripting vulnerability in the backend media pool detail page, where the opener_link parameter is rendered without HTML escaping. Unauthenticated attackers can lure logged-in backend users with media permissions into clicking a crafted link. The injected script can then read the CSRF token and perform actions with the victim's permissions, including code execution via template or module edits when the victim is an administrator.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- redaxo / core: ≥ 0; < 5.21.3 (affected, semver); 5.21.3 (unaffected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 5.1 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 6.1 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N; source: CNA: VulnCheck

- CVSS 4.0: 5.1 (medium); CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/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; source: NVD: disclosure@vulncheck.com

- CVSS 3.1: 6.1 (medium); CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N; source: NVD: disclosure@vulncheck.com

- CISA KEV: No listing in collected sources

- EPSS: 0.20% as of 2026-11-02; percentile 9.70%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-79

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/redaxo/core/security/advisories/GHSA-5293-gg47-5xmh (CNA: VulnCheck; vendor-advisory)

- https://www.vulncheck.com/advisories/redaxo-before-5.21.3-reflected-xss-via-opener-link-in-media-pool (CNA: VulnCheck; third-party-advisory)

- https://github.com/redaxo/core/security/advisories/GHSA-5293-gg47-5xmh (disclosure@vulncheck.com)

- https://www.vulncheck.com/advisories/redaxo-before-5.21.3-reflected-xss-via-opener-link-in-media-pool (disclosure@vulncheck.com)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-117535; retrieved 2026-11-02; source updated 2026-11-02

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-117535; retrieved 2026-11-02; source updated 2026-11-02

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-117535; retrieved 2026-11-02; source updated Not reported

Revision: d4972bc7b451ea93135a902d64d55dcb2d73dbf09c8cc82051080164389335ea

Canonical: https://y2.dev/cve/CVE-2026-117535

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