# CVE-2026-123864: Node.js is vulnerable to cross-connection memory disclosure via TLS write re-entrancy in the HTTPS request parser

Status: published. Published: 2026-11-11. Updated: 2026-11-11.

A re-entrancy flaw in Node.js HTTPS lets an unauthenticated client read memory belonging to other connections, including TLS private keys and other users' requests. TLSWrap::DoWrite() calls ClearOut() directly when asked to write zero bytes; if that write is issued from JavaScript running inside the HTTP parser's on_body callback, ClearOut() decrypts the next TLS record while the parser is still mid-body, re-entering llhttp_execute() and causing a use-after-free and an out-of-bounds heap read. The server then copies that freed or unrelated heap memory into the response for the request body. Triggering it requires a handler that calls res.flushHeaders() before the request body ends and later calls res.end() with a non-empty chunk, and reading the leaked memory requires any ordinary route that echoes or stores a request body. Cleartext node:http is not affected. This vulnerability affects Node.js 26.x, 24.x, and 22.x.

## Remediation

No remediation reported in collected sources

## Affected products and versions

- nodejs / node: ≥ 0.0.0; < 22.23.5 (affected, semver); ≥ 23.0.0; < 24.22.3 (affected, semver); ≥ 25.0.0; < 26.13.1 (affected, semver). Source: CNA: openjs

## Severity and prioritization

- CVSS 3.0: 8.1 (high); CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:H; source: CNA: openjs

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-416

## Exploit evidence

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

## References

- https://nodejs.org/en/blog/vulnerability/november-2026-security-releases (CNA: openjs; vendor-advisory)

- https://cna.openjsf.org/security-advisories.html (CNA: openjs)

## Provenance

- CNA: openjs: https://www.cve.org/CVERecord?id=CVE-2026-123864; retrieved 2026-11-11; source updated 2026-11-11

Revision: 043a67222dbe9ada74c6a04be271229a3449049ea0cf86f2f60eb0f9a73b0ef6

Canonical: https://y2.dev/cve/CVE-2026-123864

## 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.