CVE-2026-21637
nodejs - security update
Description
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.
How to fix CVE-2026-21637
To remediate CVE-2026-21637, upgrade the affected package to a fixed version below.
- —upgrade to 22.22.2-r0 or later
- —upgrade to 20.20.0 or later
- —upgrade to 20.20.0 or later
- —upgrade to 12.22.12~dfsg-1~deb11u8 or later
- —upgrade to 20.19.2+dfsg-1+deb13u2 or later
Is CVE-2026-21637 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (5)
- from 0, < 22.22.2-r0
- from 0, < 20.20.0, >= 21.0.0, < 22.22.0, >= 23.0.0, < 24.13.0, >= 25.0.0, < 25.3.0
- from 0, < 20.20.0, >= 21.0.0, < 22.22.0, >= 23.0.0, < 24.13.0, >= 25.0.0, < 25.3.0
- from 0, < 12.22.12~dfsg-1~deb11u8
- from 0, < 20.19.2+dfsg-1+deb13u2
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 3.1 | HIGH7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |