CVE-2026-123871: Information Disclosure (CVSS 6.2)

Description

Node.js discloses proxy credentials in ERR_PROXY_INVALID_CONFIG error messages. CVE-2026-48615 established that a proxy credential must not appear in a Node.js error message and redacted the username and password from ProxyConfig.href, but that fix missed four error paths in the same subsystem, one of them inside the same constructor, which interpolate the raw proxy URL, credentials included, into an ERR_PROXY_INVALID_CONFIG message. The proxy URL comes from the environment, but the defect is the sink: a secret that Node.js redacts everywhere else is emitted verbatim into a much wider audience than the process environment, such as stderr, container logs, log aggregation, and crash reporting services. This vulnerability affects Node.js 26.x, 24.x, and 22.x.

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CVSS v3.1 Score

6.2

MEDIUM

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

EPSS — Exploit Prediction

0.0016

Probability of exploitation

0.05%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-209 CWE-209

References

Other References

https://cna.openjsf.org/security-advisories.html https://nodejs.org/en/blog/vulnerability/november-2026-security-releases

Frequently Asked Questions

What is CVE-2026-123871? +

Node.js discloses proxy credentials in ERR_PROXY_INVALID_CONFIG error messages. CVE-2026-48615 established that a proxy credential must not appear in a Node.js error message and redacted the username and password from ProxyConfig.href, but that fix missed four error paths in the same subsystem, one of them inside the same constructor, which interpolate the raw proxy URL, credentials included, into an ERR_PROXY_INVALID_CONFIG message. The proxy URL comes from the environment, but the defect is the sink: a secret that Node.js redacts everywhere else is emitted verbatim into a much wider audience than the process environment, such as stderr, container logs, log aggregation, and crash reporting services. This vulnerability affects Node.js 26.x, 24.x, and 22.x. It has a CVSS v3.1 base score of 6.2 (MEDIUM).

How severe is CVE-2026-123871? +

CVE-2026-123871 has a CVSS v3.1 score of 6.2 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0016, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-123871? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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