CVE-2026-21637

At a glance

Severity
MEDIUM 5.9
EPSS
EPSS 1.12 % · percentile 66 (2026-10-27)
State
PUBLISHED
Published
Updated
Assigner
hackerone
NVD status
Analyzed

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.

Scores

VersionScoreVectorScored by
CVSS 3.0MEDIUM 5.9CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:Hhackerone
CVSS 3.1HIGH 7.5CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HNVD · nvd@nist.gov (Primary)
CVSS 3.0MEDIUM 5.9CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:HNVD · support@hackerone.com (Secondary)

Weaknesses (CWE)

European references

CERT-FR advisories

Affected configurations (NVD CPE)

Affected products

ProductVersions
nodejs · nodeaffected 20.19.6 ≤ 20.19.6 ; affected 22.21.1 ≤ 22.21.1 ; affected 24.12.0 ≤ 24.12.0 ; affected 25.2.1 ≤ 25.2.1 ; affected 4.0 < 4.* ; affected 5.0 < 5.*

References

Sources

SourceLicence
CVE List (CVEProject cvelistV5)CVE Program Terms of Use
EPSS (FIRST.org)FIRST — attribution requested
ENISA EUVDENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feedsPublic domain — this product uses data from the NVD API but is not endorsed or certified by the NVD