Memory leak and DoS in Node.js HTTP/2 via crafted WINDOW_UPDATE frames
CVE-2026-21714 is a medium-severity denial-of-service vulnerability in Node.js HTTP/2 server implementations affecting Node.js 20.x, 22.x, 24.x, and 25.x. A malicious client can send HTTP/2 WINDOW_UPDATE frames on stream 0 (the connection-level control stream) with values that cause the flow-control window to exceed the protocol maximum of 2^31-1. In the affected implementation, this triggers an NGHTTP2_ERR_FLOW_CONTROL condition. Although the server correctly responds by sending a GOAWAY frame, the associated Http2Session object is not cleaned up afterward, resulting in a memory leak. Repeated exploitation across connections can accumulate leaked session objects and exhaust server memory.
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Impact, mitigation & remediation
What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.
Impact
What an attacker gets, and what they’ve been doing with it.
Mitigation
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Remediation
Patch, then assume compromise.
Exploits
No public exploits tracked yet. Mallory keeps watching.
No public exploit code observed for this vulnerability.
Affected products & vendors
Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.
Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.
Recent activity
9 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A Node.js HTTP/2 server memory leak vulnerability where abused WINDOW_UPDATE frames can cause resource exhaustion because Http2Session is not cleaned up after GOAWAY.
A medium-severity Node.js HTTP/2 flow-control handling flaw that allows malformed frames to trigger memory leaks and denial-of-service.
The version that knows your environment.
Query your assets running an affected version, and investigate the blast radius.
Every observed campaign linking this CVE to a named adversary.
Malware families riding this exploit, with evidence and IOCs.
YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.
Cross-references every affected SKU, including bundled OEM variants.
Community discussion across Reddit, Mastodon, and other social sources.