PostgreSQL JDBC Driver / SCRAM Client, Silent Channel-Binding Downgrade, CVE-2026-54291 (Medium) -DC-Jul2026-819

</code>) via the deprecated `getChannelBindingData()` API.
2. Misinterpretation by Client Builder: The client builder incorrectly interprets this empty byte array as an environmental absence of channel binding data (rather than a cryptographic failure) and falls back to non-channel-bound authentication.
The impact is limited to deployments that explicitly enforce strict channel binding—for example, by setting `channelBinding=require` in pgJDBC. Under the default `prefer` policy (or <code>allow</code>/<code>disable</code>), falling back to plain SCRAM is documented behavior, so these configurations are not vulnerable to this specific downgrade.
The issue has been addressed in `scram-client` version 3.3, which introduces strict exception propagation and explicit policy controls. Additionally, pgJDBC 42.7.12 enforces channel binding in the driver's own code, failing the connection when no binding data can be extracted.

<h2 style="color: blue;">DailyCVE Form</h2>

<h2 style="color: blue;">| Field | Value |</h2>

<h2 style="color: blue;">|-|-|</h2>

<h2 style="color: blue;">| Platform | PostgreSQL JDBC |</h2>

<h2 style="color: blue;">| Version | 42.7.4–42.7.11 |</h2>

<h2 style="color: blue;">| Vulnerability | Channel-binding downgrade |</h2>

<h2 style="color: blue;">| Severity | Medium |</h2>

<h2 style="color: blue;">| Date | 2026-06-30 |</h2>

<h2 style="color: blue;">| Prediction | Patch already released |</h2>

<h2 style="color: blue;">What Undercode Say</h2>

The following analytics and verification steps can be used to assess exposure and validate the fix:
[bash]
Check pgJDBC version in your project
mvn dependency:tree | grep postgresql
Check scram-client version (bundled dependency)
mvn dependency:tree | grep scram-client
For Gradle projects
gradle dependencies | grep postgresql
gradle dependencies | grep scram-client

Code snippet demonstrating the vulnerable behavior (conceptual):

// Vulnerable approach (pre-3.3)
TlsServerEndpoint endpoint = ...;
byte[] bindingData = endpoint.getChannelBindingData(); // returns empty byte[] on failure
// Client builder treats empty array as "no binding data available" and downgrades

Code snippet showing the fixed implementation (scram-client 3.3+):

// Fixed approach (3.3+)
ScramClient client = ScramClient.builder()
.advertisedMechanisms(serverMechanisms)
.username(user)
.password(pass)
.channelBindingPolicy(ChannelBindingPolicy.REQUIRE) // Explicit enforcement
.channelBinding(TlsServerEndpoint.TLS_SERVER_END_POINT, certHash)
.build();

Dependency update (Maven) :

<dependency>
<groupId>com.ongres.scram</groupId>
<artifactId>scram-client</artifactId>
<version>3.3</version>
</dependency>

Dependency update (Gradle) :

implementation 'com.ongres.scram:scram-client:3.3'

For pgJDBC users, upgrading to version 42.7.12 or later is recommended, as it enforces channel binding at the driver level:

<dependency>
<groupId>org.postgresql</groupId>
<artifactId>postgresql</artifactId>
<version>42.7.12</version>
</dependency>

How Exploit

1. Positioning: The attacker establishes a TLS man-in-the-middle position between the client and the server.
2. Certificate Selection: The attacker presents an X.509 certificate signed with a modern algorithm lacking traditional `WITH` naming structures—such as Ed25519, Ed448, or a post-quantum algorithm.
3. Triggering the Bug: The server's certificate causes the `TlsServerEndpoint.getChannelBindingData()` method to fail silently, returning an empty byte array instead of throwing an exception.
4. Downgrade: The client builder misinterprets the empty byte array as an absence of channel binding data and falls back to standard SCRAM-SHA-256 authentication, bypassing channel binding.
5. Result: The connection proceeds without channel binding, stripping away MITM protection even though `channelBinding=require` was set.

Protection

• Upgrade the SCRAM library to version 3.3 or later.
• For pgJDBC users, upgrade to version 42.7.12 or later.
• If using the `ScramClient` builder API directly, migrate from the deprecated `TlsServerEndpoint.getChannelBindingData()` to TlsServerEndpoint.getChannelBindingHash(), which correctly propagates NoSuchAlgorithmException.
• Adopt explicit policies using the newly introduced `ChannelBindingPolicy` API during client construction, rather than relying on implicit parameter presence.
• Audit application configurations to ensure that `channelBinding=require` is not being used with vulnerable library versions.

Impact

• Confidentiality: A successful MITM attacker can intercept and read authentication credentials and subsequent session traffic.
• Integrity: The attacker can modify communications between the client and server without detection.
• Authentication Bypass: Channel binding—the mechanism designed to bind the authentication to the TLS channel—is silently disabled, undermining the security guarantee that `channelBinding=require` is meant to provide.
• Affected Deployments: Only applications that explicitly set `channelBinding=require` are impacted; the default `prefer` policy is not vulnerable.
• Affected Versions: pgJDBC 42.7.4 through 42.7.11 (bundling scram-client 3.1 or 3.2). Versions before 42.7.4 are unaffected as they do not support channel binding.

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Sources:

Reported By: github.com
Extra Source Hub:
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