Summary
Redaxo has Path Traversal in Backup Addon Leading to Arbitrary File Read
Impact
Full compromise of the REDAXO installation:
- Database takeover
- Password hash extraction → offline cracking → admin access
- When combined with other vulnerabilities → RCE
CVSS 4.0 vector & score below.
Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files. Typical impact: unauthorized file read or write outside the intended directory.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-21857? CVE-2026-21857 is a high-severity path traversal vulnerability in redaxo/source (composer), affecting versions <= 5.20.1. It is fixed in 5.20.2. Input manipulates file paths to reach files outside the intended directory, such as configuration or credential files.
- Which versions of redaxo/source are affected by CVE-2026-21857? redaxo/source (composer) versions <= 5.20.1 is affected.
- Is there a fix for CVE-2026-21857? Yes. CVE-2026-21857 is fixed in 5.20.2. Upgrade to this version or later.
- Is CVE-2026-21857 exploitable, and should I be worried? Whether CVE-2026-21857 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-21857 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-21857? Upgrade
redaxo/sourceto 5.20.2 or later.