CVE-2026-4926
7.5 · HIGHImpact: A bad regular expression is generated any time you have multiple sequential optional groups (curly brace syntax), such as `{a}{b}{c}:z`.
Overview
CVE-2026-4926 is a high-severity vulnerability affecting pillarjs path-to-regexp. It was published on March 26, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
Technical description
Impact:
A bad regular expression is generated any time you have multiple sequential optional groups (curly brace syntax), such as `{a}{b}{c}:z`. The generated regex grows exponentially with the number of groups, causing denial of service.
Patches:
Fixed in version 8.4.0.
Workarounds:
Limit the number of sequential optional groups in route patterns. Avoid passing user-controlled input as route patterns.
Remediation
Check the references section for vendor advisories and patches from pillarjs. Update path-to-regexp to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
Affected products
| Vendor | Product | Versions | Status |
|---|---|---|---|
| pillarjs | path-to-regexp | >= 8.0.0, < 8.4.0 | Affected |
References
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Frequently asked questions
What is CVE-2026-4926?
CVE-2026-4926 is a high-severity vulnerability affecting pillarjs path-to-regexp. It was published on March 26, 2026 and has a CVSS 3.1 base score of 7.5 (HIGH).
How severe is CVE-2026-4926?
This vulnerability has a CVSS 3.1 base score of 7.5, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.
How do I fix or remediate CVE-2026-4926?
Check the references section for vendor advisories and patches from pillarjs. Update path-to-regexp to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-4926?
CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-4926 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.
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