Summary
Workarounds
Unset the X-Original-Url header in the web server configuration.
References
The activation of these headers is coming from the Zend_Controller module. It appears this has been known to some degree since 2016 -
https://peterocallaghan.co.uk/2016/12/magento-poisoning-cache/ (dead link now..)
Credit
Anees Hyder ( @anees0xdev ) via HackerOne
https://hackerone.com/anees0x_dev/hacktivity
Impact
The admin url can be discovered without prior knowledge of it's location by exploiting the X-Original-Url header on some configurations.
CVE-2026-25523 has a CVSS score of 5.3 (Medium). The vector is network-reachable, no privileges required, and no user interaction. A CVSS score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether this affects your application depends on whether the vulnerable code is present and reachable in your environment. A fixed version is available (20.16.1); upgrading removes the vulnerable code path.
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
The bug comes from the Zend library and is patche by unsetting the header in the bootstrap process.
Frequently Asked Questions
- What is CVE-2026-25523? CVE-2026-25523 is a medium-severity security vulnerability in openmage/magento-lts (composer), affecting versions < 20.16.1. It is fixed in 20.16.1.
- How severe is CVE-2026-25523? CVE-2026-25523 has a CVSS score of 5.3 (Medium). This score reflects the worst-case severity of the vulnerability, not your specific exposure. Whether it represents real risk in your environment depends on whether the vulnerable code is present and reachable.
- Which versions of openmage/magento-lts are affected by CVE-2026-25523? openmage/magento-lts (composer) versions < 20.16.1 is affected.
- Is there a fix for CVE-2026-25523? Yes. CVE-2026-25523 is fixed in 20.16.1. Upgrade to this version or later.
- Is CVE-2026-25523 exploitable, and should I be worried? Whether CVE-2026-25523 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-2026-25523 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-2026-25523? Upgrade
openmage/magento-ltsto 20.16.1 or later.