blog: March 2026 security releases (#2226)

Co-authored-by: Sebastian Beltran <bjohansebas@gmail.com>

Author: UlisesGascon

_posts/2026-03-30-security-releases.md

@@ -0,0 +1,62 @@
+---
+title: March 2026 Security Releases
+description: Security releases for path-to-regexp have been published. We recommend that all users upgrade as soon as possible.
+tags: security vulnerabilities
+authors:
+  - name: Ulises Gascon
+    github: UlisesGascon
+---
+
+The Express team has released new patch versions of [path-to-regexp](https://www.npmjs.com/package/path-to-regexp) addressing three regular expression denial of service vulnerabilities.
+
+{% capture warning_content %}
+We recommend upgrading to the latest version of path-to-regexp to secure your applications. If you have a `package-lock.json`, you can update the dependency by running:
+
+```sh
+npm update path-to-regexp
+```
+{% endcapture %}
+{% include admonitions/warning.html content=warning_content %}
+
+The following vulnerabilities have been addressed:
+
+- [CVE-2026-4867 in path-to-regexp utility module (High)](#cve-2026-4867-in-path-to-regexp-utility-module-high)
+- [CVE-2026-4926 in path-to-regexp utility module (High)](#cve-2026-4926-in-path-to-regexp-utility-module-high)
+- [CVE-2026-4923 in path-to-regexp utility module (Medium)](#cve-2026-4923-in-path-to-regexp-utility-module-medium)
+
+## CVE-2026-4867 in path-to-regexp utility module (High)
+
+**[path-to-regexp](https://www.npmjs.com/package/path-to-regexp) versions `<= 0.1.12` are vulnerable to regular expression denial of service via multiple route parameters**
+
+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`. The backtrack protection added in v0.1.12 only prevents ambiguity for two parameters. With three or more, the generated lookahead does not block single separator characters, causing catastrophic backtracking.
+
+**Affected versions**: `<= 0.1.12`
+**Patched version**: `>= 0.1.13`
+
+For more details, see [GHSA-37ch-88jc-xwx2](https://github.com/pillarjs/path-to-regexp/security/advisories/GHSA-37ch-88jc-xwx2).
+
+## CVE-2026-4926 in path-to-regexp utility module (High)
+
+**[path-to-regexp](https://www.npmjs.com/package/path-to-regexp) versions `>= 8.0.0` are vulnerable to denial of service via sequential optional groups**
+
+A bad regular expression is generated any time you have multiple sequential optional groups, such as `{a}{b}{c}:z`. The generated regex grows exponentially with the number of groups, causing denial of service. Avoid passing user-controlled input as route patterns.
+
+**Affected versions**: `>= 8.0.0`
+**Patched version**: `>= 8.4.0`
+
+For more details, see [GHSA-j3q9-mxjg-w52f](https://github.com/pillarjs/path-to-regexp/security/advisories/GHSA-j3q9-mxjg-w52f).
+
+## CVE-2026-4923 in path-to-regexp utility module (Medium)
+
+**[path-to-regexp](https://www.npmjs.com/package/path-to-regexp) versions `>= 8.0.0, <= 8.3.0` are vulnerable to regular expression denial of service via multiple wildcards**
+
+When using multiple wildcards combined with at least one parameter, a regular expression can be generated that is vulnerable to ReDoS. The second wildcard must be somewhere other than the end of the path. For example, `/*foo-*bar-:baz`.
+
+**Affected versions**: `>= 8.0.0, <= 8.3.0`
+**Patched version**: `>= 8.4.0`
+
+For more details, see [GHSA-27v5-c462-wpq7](https://github.com/pillarjs/path-to-regexp/security/advisories/GHSA-27v5-c462-wpq7).
+
+---
+
+We recommend upgrading to the latest version of path-to-regexp to secure your applications.