CVE-2026-21637 (GCVE-0-2026-21637)

Vulnerability from cvelistv5 – Published: 2026-01-20 20:41 – Updated: 2026-01-21 20:22
VLAI
Summary
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.
Severity
5.9 (Medium)
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: yes Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-400 - Uncontrolled Resource Consumption
Assigner
References
Impacted products
Vendor Product Version
nodejs node Affected: 20.19.6 , ≤ 20.19.6 (semver)
Affected: 22.21.1 , ≤ 22.21.1 (semver)
Affected: 24.12.0 , ≤ 24.12.0 (semver)
Affected: 25.2.1 , ≤ 25.2.1 (semver)
Affected: 4.0 , < 4.* (semver)
Affected: 5.0 , < 5.* (semver)
Affected: 6.0 , < 6.* (semver)
Affected: 7.0 , < 7.* (semver)
Affected: 8.0 , < 8.* (semver)
Affected: 9.0 , < 9.* (semver)
Affected: 10.0 , < 10.* (semver)
Affected: 11.0 , < 11.* (semver)
Affected: 12.0 , < 12.* (semver)
Affected: 13.0 , < 13.* (semver)
Affected: 14.0 , < 14.* (semver)
Affected: 15.0 , < 15.* (semver)
Affected: 16.0 , < 16.* (semver)
Affected: 17.0 , < 17.* (semver)
Affected: 18.0 , < 18.* (semver)
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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.