# CVE-2026-62864: Ring's nested-params middleware has inefficient regular expression complexity

Status: published. Published: 2026-10-30. Updated: 2026-11-02.

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.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- ring-clojure / ring: < 1.15.5 (affected). Source: CNA: GitHub_M

## Severity and prioritization

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: CNA: GitHub_M

- CVSS 3.1: 7.5 (high); CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H; source: NVD: security-advisories@github.com

- CISA KEV: No listing in collected sources

- EPSS: 0.34% as of 2026-11-02; percentile 27.34%

- SSVC: exploitation none; automatable yes; technical impact partial; source ADP: CISA-ADP

- Weaknesses: CWE-1333

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/ring-clojure/ring/security/advisories/GHSA-q2j3-fc6x-78jj (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/ring-clojure/ring/commit/18738cbb8ab7504da4a5c72c9eb5fdcbf142646e (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/ring-clojure/ring/tree/1.15.5 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/ring-clojure/ring/commit/18738cbb8ab7504da4a5c72c9eb5fdcbf142646e (security-advisories@github.com)

- https://github.com/ring-clojure/ring/security/advisories/GHSA-q2j3-fc6x-78jj (security-advisories@github.com)

- https://github.com/ring-clojure/ring/tree/1.15.5 (security-advisories@github.com)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-62864; retrieved 2026-11-02; source updated 2026-11-02

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-62864; retrieved 2026-11-02; source updated 2026-11-02

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2026-62864; retrieved 2026-11-02; source updated Not reported

Revision: 1129a5220a372498c403e97786324ed1f18208db6b978b184102bd80868ad31d

Canonical: https://y2.dev/cve/CVE-2026-62864

## Agent and API access

Public CVE pages, Markdown, and JSON are free to read without an account or API key.

- Public catalog: https://y2.dev/cve/index.json. Follow nextCursor with the same search, filters, sort, and limit (1–100). A null cursor marks the end.

- WebMCP: search_cve_disclosures, get_cve_disclosure, get_cve_page_markdown, get_y2_cve_access. Available in compatible browsers.

- Cyber API: https://api.y2.dev/api/v2/cyber/cves and https://api.y2.dev/api/v2/cyber/cves/{cveId}.

- Y2 Pro or Elite: create a workspace API key with the intel:cyber scope and send Authorization: Bearer <Y2_API_KEY>. Setup: https://y2.dev/docs/api/create-key.

- x402: Pay per request without an account or API key. Omit Authorization, read the HTTP 402 PAYMENT-REQUIRED challenge, validate its current requirements, and retry with PAYMENT-SIGNATURE through an authorized payment client. These browser tools never make payments. Guide: https://y2.dev/docs/api/x402.

- OpenAPI: https://y2.dev/api/openapi.yaml. Agent access metadata: https://y2.dev/cve/agent.json.

Collected public records only. Check source status for coverage and freshness.