CVE-2026-120808: Cert Validation Flaw (CVSS 7.4)

Description

An issue exists in MongoDB's macOS TLS client implementation where certificate chain-of-trust validation is bypassed for outbound connections to IPv6-addressed peers. When a MongoDB process using the Apple SecureTransport TLS backend connects to an IPv6 target, the trust evaluation result from SecTrustEvaluate is silently discarded, regardless of whether the peer's certificate is trusted. An on-path party could exploit this by presenting a self-signed certificate containing the target's IPv6 address in the Subject Alternative Name to intercept and modify encrypted inter-node or external service traffic. This issue only affects MongoDB processes running on macOS with the Apple SecureTransport TLS provider.

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CVSS v3.1 Score

7.4

HIGH

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

EPSS — Exploit Prediction

0.0017

Probability of exploitation

0.07%

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-295 CWE-295

References

Other References

https://jira.mongodb.org/browse/SERVER-130681

Frequently Asked Questions

What is CVE-2026-120808? +

An issue exists in MongoDB's macOS TLS client implementation where certificate chain-of-trust validation is bypassed for outbound connections to IPv6-addressed peers. When a MongoDB process using the Apple SecureTransport TLS backend connects to an IPv6 target, the trust evaluation result from SecTrustEvaluate is silently discarded, regardless of whether the peer's certificate is trusted. An on-path party could exploit this by presenting a self-signed certificate containing the target's IPv6 address in the Subject Alternative Name to intercept and modify encrypted inter-node or external service traffic. This issue only affects MongoDB processes running on macOS with the Apple SecureTransport TLS provider. It has a CVSS v3.1 base score of 7.4 (HIGH).

How severe is CVE-2026-120808? +

CVE-2026-120808 has a CVSS v3.1 score of 7.4 out of 10, rated HIGH. This is a high-severity vulnerability that should be prioritized for patching. The EPSS score is 0.0017, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-120808? +

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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