Ring's nested-params middleware has inefficient regular expression complexity
Affects Ring 1.15.4 and earlier in applications that use the nested-params middleware, including Ring-Defaults users. Fixed in Ring 1.15.5.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Default setups
- Fix
- Fixed in 1.15.5
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
Ring, a Clojure web application library, is affected through its nested-params middleware (`wrap-nested-params`), including applications using Ring-Defaults since it is enabled by default. An attacker can send a crafted parameter name in a query string or request body that causes excessive processing time, leading to a denial of service.
Summarized by anthropic/claude-haiku-5.5. Verify details against the original sources.
Read the original description
Ring is a Clojure web applications library inspired by Python's WSGI and Ruby's Rack. Prior to 1.15.5, `wrap-nested-params` in the `ring.middleware.nested-params` namespace uses a backtracking regular expression to match parameter names from URL query strings and HTTP request bodies. An attacker can craft a parameter name that drives quadratic O(n^2) matching work, causing regular-expression denial of service in applications using the middleware. `Ring-Defaults` users are also exposed because nested-params is enabled by default. Applications omitting the middleware do not expose this parsing path. This issue is fixed in version 1.15.5.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- ring-clojure ring
fixed in 1.15.5
References 3
GitHub · ring-clojure/ring
Questions about CVE-2026-62864
What does this mean?
A crafted parameter name makes the nested-params regular expression take quadratic time, which consumes large amounts of CPU and affects availability (denial of service).Source: github.com
Am I affected, and how do I check?
Ring 1.15.4 and earlier are affected when an application uses the wrap-nested-params middleware, which Ring-Defaults enables by default. To check, look at the Ring version in the project dependencies and whether nested-params is in the middleware stack.Source: github.com
What should I do about it?
Upgrade to Ring 1.15.5, which patches the issue. If the nested-params middleware is not being used, omit it as a workaround.Source: github.com
Is it being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data