Security incident · CVE-2026-117538
REDAXO has reflected XSS backend packages API via function parameter (CSRF token required)
Published Apr 10, 2026 · catalog updated Oct 28, 2026 · REDAXO has reflected XSS
Last checked Oct 28, 2026. A connected source was read within the last 7 days.
Check if you run it
No confirmed exploitation is on record for CVE-2026-117538. EPSS is 0.18%. Act only if a listed version of REDAXO has reflected XSS is installed.
Gaps on this record
- The stored product name is a package slug. The name on this page is taken from the title (REDAXO has reflected XSS).
- No vendor fix or required action is stored. Compare the linked advisory before you change production.
- Severity
- Low—
- Known exploitation
- Not in CISA/VulnCheck KEV
- EPSS
- 0.18%
- Remediation
- Advisory link
- Affected products
- Packagist redaxo/source
### Summary A **reflected XSS** vulnerability has been identified in the REDAXO backend. The parameter is concatenated into an API error message and rendered without HTML escaping. --- ### Details **Root cause** User input is injected into an exception message, then rendered by which delegates to without HTML escaping. **Vulnerable code ( ) :** **Sink ( ) :** **Source -> sink flow** * Source: (GET) * Propagation: concatenated into the exception message * Sink: rendered via -> without escaping **Authentication required:** yes (backend session) --- ### PoC - Exploit To run the PoC you must set a valid admin account PHPSSID. The PoC will then automatically retrieve the CSRF token and generate a ready-to-use exploitation link. --- ### Impact * **Confidentiality:** Low : no direct session theft (HttpOnly cookies), but possibility to access/exfiltrate data available via the DOM or via same-origin requests if the XSS executes in a victim’s session. * **Integrity:** Low : possibility to chain backend actions on behalf of the user (same-origin requests) only if execution takes place in a victim session; otherwise the impact is limited to the user who triggers the call. * **Availability:** Low : the XSS could disrupt the administration interface or trigger unwanted actions, but the token requirement strongly limits realistic scenarios. ### Demo https://github.com/user-attachments/assets/41d0186a-7ca0-4482-86c5-8bea6c8f6ac6
Are you affected?
Enter the version you run. The result uses only the ranges stored on this record.
The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.
- Packagist redaxo/source0 → 5.21.0
How to fix CVE-2026-117538
Upgrade
CVE-2026-117538 lists a fix boundary at 5.21.0. Compare the installed build with that boundary before you change production.
Version check
Fixed in 5.21.0
Advisory
Open the cve_org record and follow its fix.
Official advisories
What to do
Three questions, each answered from this record only. Confirm the vendor advisory before you patch.
Should you patch?
No confirmed exploitation is on record for CVE-2026-117538. EPSS is 0.18%. Act only if a listed version of REDAXO has reflected XSS is installed.
Which versions are affected?
Compare what you have installed with 0 → 5.21.0. Compare the installed version with the linked vendor advisory before you change production.
What should an analyst verify?
CWE-79: Cross-site Scripting (XSS). EPSS 0.18%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.
Code
The project this record applies to. Exploit listings stay in References.
Timeline
Detection, updates, and resolution for this record.
Apr 10, 2026 · GitHub Advisory Database
Detected
### Summary A **reflected XSS** vulnerability has been identified in the REDAXO backend. The parameter is concatenated into an API error message and rendered without HTML escaping. --- ### Details **Root cause** User input is injected into an exception message, then rendered by which delegates to without HTML escaping. **Vulnerable code ( ) :** **Sink ( ) :** **Source -> sink flow** * Source: (GET
Oct 28, 2026 · GitHub Advisory Database
Fix available
redaxo/source fixed in 5.21.0
Oct 28, 2026 · GitHub Advisory Database
Fix available
redaxo/source fixed in 5.21.0
Oct 28, 2026 · GitHub Advisory Database
Updated
### Summary A **reflected XSS** vulnerability has been identified in the REDAXO backend. The parameter is concatenated into an API error message and rendered without HTML escaping. --- ### Details **Root cause** User input is injected into an exception message, then rendered by which delegates to without HTML escaping. **Vulnerable code ( ) :** **Sink ( ) :** **Source -> sink flow** * Source: (GET
Sources
- CVE.orgVulnerability recordCVE-2026-117538
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2026-117538
30-day exploitation probability 0.18%
first.org - GitHub Advisory DatabasePackage advisoryGHSA-xq4j-g85q-wf97
GitHub Advisory Database record mirrored by OSV.
github.com - OpenSSF OSV / OSV ScannerPackage advisoryGHSA-xq4j-g85q-wf97
REDAXO has reflected XSS backend packages API via function parameter (CSRF token required)
osv.dev
References
Freshness
Last verified in this catalog Oct 28, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.
- CVE.orgOct 28, 2026
- FIRST EPSSOct 28, 2026
- GitHub Advisory DatabaseOct 28, 2026
- OpenSSF OSV / OSV ScannerOct 28, 2026