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CVE-2026-123877

MEDIUMCVSS 6.8/10EPSS 0.21%

Last modified

CVE-2026-123877 is a medium-severity vulnerability rated 6.8/10 on the CVSS scale. A certificate validation bypass in Node.js https.Agent lets a cached TLS session authenticated under one CA policy be reused by a later request with a stricter policy. https.Agent.prototype.getName() assigns the same Agent and session-cache key to a request that omits ca and one that explicitly supplies ca: [], because an omitted value appends nothing to the key while an empty array stringifies to an empty string. EPSS estimates a 0.21% chance of exploitation in the next 30 days.

Description

A certificate validation bypass in Node.js https.Agent lets a cached TLS session authenticated under one CA policy be reused by a later request with a stricter policy. https.Agent.prototype.getName() assigns the same Agent and session-cache key to a request that omits ca and one that explicitly supplies ca: [], because an omitted value appends nothing to the key while an empty array stringifies to an empty string. The two policies differ: omitting ca uses the default trust store, while supplying ca replaces it. Since they share a key, a TLS session authenticated under the broader default policy is handed to a new connection made under the later ca: [] policy, and TLS 1.3 session resumption carries the earlier authentication forward, so the second request reports authorized === true and transmits confidential data to a server its own CA policy would reject on a fresh connection. This vulnerability affects Node.js 26.x, 24.x, and 22.x.

Metrics

CVSS 3.0
6.8/10

CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N

EPSS Probability
0.21%

11.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
nodejsnode>= 0.0.0, < 22.23.5; >= 23.0.0, < 24.22.3; >= 25.0.0, < 26.13.1

References

Timeline

Published
Last Modified
Status
Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-123877?
A certificate validation bypass in Node.js https.Agent lets a cached TLS session authenticated under one CA policy be reused by a later request with a stricter policy. https.Agent.prototype.getName() assigns the same Agent and session-cache key to a request that omits ca and one that explicitly supplies ca: [], because an omitted value appends nothing to the key while an empty array stringifies to an empty string. The two policies differ: omitting ca uses the default trust store, while supplying ca replaces it. Since they share a key, a TLS session authenticated under the broader default policy is handed to a new connection made under the later ca: [] policy, and TLS 1.3 session resumption carries the earlier authentication forward, so the second request reports authorized === true and transmits confidential data to a server its own CA policy would reject on a fresh connection. This vulnerability affects Node.js 26.x, 24.x, and 22.x.
How severe is CVE-2026-123877?
CVE-2026-123877 has a CVSS score of 6.8/10 (MEDIUM severity). The EPSS model estimates a 0.21% probability of exploitation in the next 30 days.
How do I fix CVE-2026-123877?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST