GHSA-37ch-88jc-xwx2 · Severity: high · Ecosystem: npm — path-to-regexp vulnerable to Regular Expression Denial of Service via multiple route parameters
Impact: A bad regular expression is generated any time you have three or more parameters within a single segment, separated by something that is not a period (.). For example, /:a-:b-:c or /:a-:b-:c-:d. The backtrack protection added in [email protected] only prevents ambiguity for two parameters. With three or more, the generated lookahead does not block single separator characters, so capture groups overlap and cause catastrophic backtracking. Patches: Upgrade to [email protected] Custom regex patterns in route definitions (e.g., /:a-:b([^-/]+)-:c([^-/]+)) are not affected because they override the default capture group. Workarounds: All versions can be patched by providing a custom regular expression for parameters after the first in a single segment. As long as the custom regular expression does not match the text before the parameter, you will be safe. For example, change /:a-:b-:c to /:a-:b([^-/]+)-:c([^-/]+). If paths cannot be rewritten and versions cannot be upgraded, another alternative is to limit the URL length.
Conclusion & alert: CVE-2026-4867 is rated Low Risk (31.6/100): CVSS High severity, with low exploitation likelihood (EPSS 0.02%). Mandatory action: Monitor for updates and reassess as exploit intelligence or EPSS changes.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-05-22 | 0.05% | 0.02% | -0.03% |
| 2 | 2026-04-01 | 0.04% | 0.05% | +0.01% |
| 3 | 2026-03-27 | — | 0.04% | — |
Full EPSS history (3 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 7.5 | 3.1 | HIGH |
|
3.9 | 3.6 | ce714d77-add3-4f53-aff5-83d477b104bb |
GHSA-37ch-88jc-xwx2 · Severity: high · Ecosystem: npm — path-to-regexp vulnerable to Regular Expression Denial of Service via multiple route parameters
| vendor | priority | summary | link |
|---|---|---|---|
debian
|
not yet assigned | CVE-2026-4867 not yet assigned priority: Debian including 1 source packages (node-path-to-regexp), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. | https://security-tracker.debian.org/tracker/CVE-2026-4867 |
redhat
|
medium | — | https://access.redhat.com/security/cve/CVE-2026-4867 |
ubuntu
|
medium | CVE-2026-4867 medium priority: Ubuntu including 1 source packages (node-path-to-regexp), 7 status rows across 7 suites (bionic, focal, jammy, noble, questing, upstream, xenial): needs-triage 3, not-affected 3, released 1. | https://ubuntu.com/security/CVE-2026-4867 |
| Vendor | Product | Version | Raw CPE |
|---|---|---|---|
| pillarjs | path-to-regexp | < 0.1.13 | cpe:2.3:a:pillarjs:path-to-regexp:*:*:*:*:*:node.js:*:* |
| URL | Tags |
|---|---|
| https://blakeembrey.com/posts/2024-09-web-redos | Technical Description |
| https://cna.openjsf.org/security-advisories.html | Third Party Advisory |
| https://github.com/advisories/GHSA-9wv6-86v2-598j | Not Applicable |