CVE-2026-21637: nodejs vulnerability
nodejs · node
Vendor fix available · Affected: nodejs · Exploitation: possible (1 to 10%)
Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.
Higher than 66% of scored CVEs
DescriptionCVE.org
A flaw in Node.js TLS error handling allows remote attackers to crash or exhaust resources of a TLS server when `pskCallback` or `ALPNCallback` are in use. Synchronous exceptions thrown during these callbacks bypass standard TLS error handling paths (tlsClientError and error), causing either immediate process termination or silent file descriptor leaks that eventually lead to denial of service. Because these callbacks process attacker-controlled input during the TLS handshake, a remote client can repeatedly trigger the issue. This vulnerability affects TLS servers using PSK or ALPN callbacks across Node.js versions where these callbacks throw without being safely wrapped.
Affected products1
From the CVE record. A product or version that is not listed is unknown, not unaffected.
- nodejs · nodefrom 20.19.6 up to and including 20.19.6; from 22.21.1 up to and including 22.21.1; from 24.12.0 up to and including 24.12.0; from 25.2.1 up to and including 25.2.1; from 4.0 before 4.*; from 5.0 before 5.* and 13 more
On the Atlas
Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.
- Exploitation
- Possible (1 to 10%). EPSS between 1% and 10%.
- CISA KEV
- Not listed
- Public check
- No public nuclei template
- Vendor
- nodejs
- Published
- January 2026
- Bounty reports
- 3 disclosed on HackerOne
Disclosed bug bounty reports about CVE-2026-21637
The reports on HackerOne that name this CVE, with HackerOne's own outcome. Titles and metadata only.
- TLS PSK/ALPN Callback Exceptions Bypass Error Handlers, Causing DoS and FD LeakNode.js · 2026 · medium severityValid
- Incomplete fix for CVE-2026-21637: loadSNI() in _tls_wrap.js lacks try/catch leading to Remote DoSNode.js · 2026 · high severityValid
- Incomplete Fix for CVE-2026-21637: OCSPRequest and resumeSession Events Crash Node.js TLS Server via Unhandled Synchronous ExceptionsNode.js · 2026 · high severityInformative
CoverageNo articles yet
No CyberSIXT article names CVE-2026-21637 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.