CVE-2026-126837 (CVSS 7.4)

Description

A validation flaw in the DNS SRV host discovery of the MongoDB Node.js driver may cause the driver to connect to a host outside the expected domain. For a mongodb+srv:// connection string, the driver checks each host name in the DNS SRV response against the domain of the connection string. The driver then builds the connection address from the original name, in which certain characters end the host name early. An unauthenticated party who can forge or change the DNS SRV response may redirect the connection to a host of their choice. TLS does not prevent this, because the driver verifies the server certificate against the redirected host name. This may result in unintended disclosure of application data and authentication credentials, and in altered query results. Applications that use mongodb:// connection strings are not affected.

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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

Weakness Type (CWE)

CWE-180 CWE-180

References

Other References

https://jira.mongodb.org/browse/NODE-7830

Frequently Asked Questions

What is CVE-2026-126837? +

A validation flaw in the DNS SRV host discovery of the MongoDB Node.js driver may cause the driver to connect to a host outside the expected domain. For a mongodb+srv:// connection string, the driver checks each host name in the DNS SRV response against the domain of the connection string. The driver then builds the connection address from the original name, in which certain characters end the host name early. An unauthenticated party who can forge or change the DNS SRV response may redirect the connection to a host of their choice. TLS does not prevent this, because the driver verifies the server certificate against the redirected host name. This may result in unintended disclosure of application data and authentication credentials, and in altered query results. Applications that use mongodb:// connection strings are not affected. It has a CVSS v3.1 base score of 7.4 (HIGH).

How severe is CVE-2026-126837? +

CVE-2026-126837 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.

How do I check if I'm vulnerable to CVE-2026-126837? +

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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