CVE-2026-4923
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedImpact: When using multiple wildcards, combined with at least one parameter, a regular expression can be generated that is vulnerable to ReDoS. This backtracking vulnerability requires the second wildcard to be somewhere other than the end of the path. Unsafe examples: /*foo-*bar-:baz /*a-:b-*c-:d /x/*a-:b/*c/y Safe examples: /*foo-:bar /*foo-:bar-*baz Patches: Upgrade to version 8.4.0. Workarounds: If you are using multiple wildcard parameters, you can check the regex output with a tool such as https://makenowjust-labs.github.io/recheck/playground/ to confirm whether a path is vulnerable.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThis is a ReDoS (Regular Expression Denial of Service) vulnerability in a path matching/routing library where certain combinations of multiple wildcards with parameters generate vulnerable regex patterns due to catastrophic backtracking. Specifically, paths with a second wildcard not at the end of the path (e.g., /*foo-*bar-:baz) are vulnerable.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data>= 8.0.0, < 8.4.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify Path To Regexp versionCheck package.json or lock file for the installed version of path-to-regexp, or run 'npm list path-to-regexp' in the project directoryAffected if The installed version is >= 8.0.0 and < 8.4.0
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Review route pattern definitionsSearch codebase for path-to-regexp usage, specifically look for route pattern definitions or route configuration files where path patterns are definedAffected if Any route patterns contain multiple wildcards where a second wildcard appears before the end of the path (e.g., patterns containing /*something-*something-else or similar multi-wildcard constructions)
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Identify path matching configurationLocate where path-to-regexp is imported and used in routing middleware or route handlersAffected if The application uses path-to-regexp for routing and processes user-controlled paths against patterns with multiple wildcards not at the end
You are affected if Path To Regexp version is between 8.0.0 and 8.3.x inclusive AND your application processes routes with patterns containing multiple wildcards where a second wildcard appears before the path end.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped8.4.0
Upgrade to version 8.4.0 or later to receive the patch. Review existing route patterns against the vulnerable examples provided and test with tools like recheck if unable to upgrade immediately.
8.4.0
- Run `npm install [email protected]` or `yarn add [email protected]` to update to the patched version
- Verify the update was successful by checking your package.json or running `npm list path-to-regexp`
- If using multiple wildcard parameters, optionally validate the generated regex using https://makenowjust-labs.github.io/recheck/playground/ to confirm the vulnerability is resolved
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation2.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-4923 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-4923 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
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