MongoDB Node.js Driver DNS SRV Host Validation Bypass
CVE-2026-126837 Published on November 12, 2026
Attacker able to redirect a client's database traffic to a host they control via special characters in an SRV target, bypassing the SRV parent-domain guard
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.
Vulnerability Analysis
CVE-2026-126837 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity and availability.
Weakness Type
Incorrect Behavior Order: Validate Before Canonicalize
The software validates input before it is canonicalized, which prevents the software from detecting data that becomes invalid after the canonicalization step. This can be used by an attacker to bypass the validation and launch attacks that expose weaknesses that would otherwise be prevented, such as injection.
Affected Versions
MongoDB Node.js Driver:- Version 3.3.3 and below 7.8.0 is affected.
Exploit Probability
EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.