CVE-2026-21637

Published Jan 20, 2026

Last updated a month ago

CVSS high 7.5
AWS
Tls

Overview

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.
Source
support@hackerone.com
NVD status
Analyzed
Products
node.js

Risk scores

CVSS 3.1

Type
Primary
Base score
7.5
Impact score
3.6
Exploitability score
3.9
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Severity
HIGH

CVSS 3.0

Type
Secondary
Base score
5.9
Impact score
3.6
Exploitability score
2.2
Vector string
CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Severity
MEDIUM

Weaknesses

134c704f-9b21-4f2e-91b3-4a467353bcc0
CWE-400

Social media

Hype score
Not currently trending

Configurations

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  4. Issue summary: PBMAC1 parameters in PKCS#12 files are missing validation which can trigger a stack-based buffer overflow, invalid pointer or NULL pointer dereference during MAC verification. Impact summary: The stack buffer overflow or NULL pointer dereference may cause a crash leading to Denial of Service for an application that parses untrusted PKCS#12 files. The buffer overflow may also potentially enable code execution depending on platform mitigations. When verifying a PKCS#12 file that uses PBMAC1 for the MAC, the PBKDF2 salt and keylength parameters from the file are used without validation. If the value of keylength exceeds the size of the fixed stack buffer used for the derived key (64 bytes), the key derivation will overflow the buffer. The overflow length is attacker-controlled. Also, if the salt parameter is not an OCTET STRING type this can lead to invalid or NULL pointer dereference. Exploiting this issue requires a user or application to process a maliciously crafted PKCS#12 file. It is uncommon to accept untrusted PKCS#12 files in applications as they are usually used to store private keys which are trusted by definition. For this reason the issue was assessed as Moderate severity. The FIPS modules in 3.6, 3.5 and 3.4 are not affected by this issue, as PKCS#12 processing is outside the OpenSSL FIPS module boundary. OpenSSL 3.6, 3.5 and 3.4 are vulnerable to this issue. OpenSSL 3.3, 3.0, 1.1.1 and 1.0.2 are not affected by this issue as they do not support PBMAC1 in PKCS#12.•CVE-2025-11187
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References

Sources include official advisories and independent security research.