Summary
OpenRun: Redirect URL validation bypass using //host paths leads to Open Redirect
The restrictions on redirect URLs in openrun can be bypassed by attackers, leading to open redirect attacks.
Details
In the current project, the referrer header value is used for subsequent redirects, so there is currently a validation for this redirect value. The current validation logic requires that the host and schema of the redirect URL be the same as the current website's URL, and finally, the path part is used for redirection. This check seems robust, but it can still be bypassed by attackers.
Here's the problem: Assuming the current website is http://127.0.0.1:25222/, if the attacker passes in a redirect URL of http://127.0.0.1:25222//fushuling.com, its host and schema are obviously the same as the current website, thus bypassing the verification. However, the issue lies in the final redirect URL, which is the path part of the URL, i.e., //fushuling.com.
Browsers automatically complete the HTTP header for URLs starting with //, ultimately successfully bypassing the restriction and redirecting to the external address http://fushuling.com.
This vulnerable behavior was successfully reproduced locally. Normally, specifying an external address directly will be blocked, so it will not redirect.
However, if the redirect URL is http://127.0.0.1:25222//fushuling.com, the existing validation logic is bypassed, and the Location header is successfully set to //fushuling.com.
POST /redirecttest/abc/frag HTTP/1.1
Host: 127.0.0.1:25222
Referer: http://127.0.0.1:25222//fushuling.com
Cache-Control: max-age=0
sec-ch-ua: "Not(A:Brand";v="24", "Chromium";v="122"
sec-ch-ua-mobile: ?0
sec-ch-ua-platform: "Windows"
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.6261.57 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.7
Sec-Fetch-Site: none
Sec-Fetch-Mode: navigate
Sec-Fetch-User: ?1
Sec-Fetch-Dest: document
Accept-Encoding: gzip, deflate, br
Accept-Language: zh-CN,zh;q=0.9
Connection: close
Content-Type: application/x-www-form-urlencoded
Content-Length: 0
The user was then successfully redirected to the external address http://fushuling.com.
PoC
http://127.0.0.1:25222//fushuling.com
Impact
Open Redirect
Untrusted input controls a URL used for redirection, which can forward users to attacker-controlled sites. Typical impact: phishing and credential harvesting via a trusted domain.
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.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2026-55252? CVE-2026-55252 is a medium-severity open redirect vulnerability in github.com/openrundev/openrun (go), affecting versions < 0.17.7. It is fixed in 0.17.7. Untrusted input controls a URL used for redirection, which can forward users to attacker-controlled sites.
- Which versions of github.com/openrundev/openrun are affected by CVE-2026-55252? github.com/openrundev/openrun (go) versions < 0.17.7 is affected.
- Is there a fix for CVE-2026-55252? Yes. CVE-2026-55252 is fixed in 0.17.7. Upgrade to this version or later.
- Is CVE-2026-55252 exploitable, and should I be worried? Whether CVE-2026-55252 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-2026-55252 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-2026-55252? Upgrade
github.com/openrundev/openrunto 0.17.7 or later.