CVE-2025-59432: SCRAM Java Auth Bypass Vulnerability

CVE-2025-59432 Overview

CVE-2025-59432 is a timing side-channel vulnerability in the SCRAM (Salted Challenge Response Authentication Mechanism) Java implementation maintained by ongres. Versions prior to 3.2 use Arrays.equals to compare secret values such as client proofs and server signatures. Because Arrays.equals performs a short-circuit comparison, the execution time varies based on how many leading bytes match. An attacker measuring these timing differences can incrementally infer authentication material. The flaw is tracked as CWE-208: Observable Timing Discrepancy and affects all users relying on SCRAM authentication provided by the ongres/scram library.

Critical Impact
A network-based attacker without prior authentication can exploit timing differences during SCRAM authentication to progressively recover client proofs or server signatures, potentially exposing sensitive credential material.

Affected Products

ongres SCRAM Java library, versions prior to 3.2
Applications embedding the ongres/scram library for SASL SCRAM authentication
Downstream projects using SCRAM authentication provided by the affected library (for example, PostgreSQL Java drivers and connectors that depend on ongres/scram)

Discovery Timeline

2025-09-22 - CVE-2025-59432 published to the National Vulnerability Database (NVD)
2026-06-17 - Last updated in the NVD database

Technical Details for CVE-2025-59432

Vulnerability Analysis

SCRAM is a challenge-response authentication family defined by the Simple Authentication and Security Layer (SASL, RFC 4422). During authentication, both the client and server compute cryptographic proofs and exchange them for verification. The ongres/scram Java library performed these equality checks using java.util.Arrays.equals, which returns as soon as the first differing byte is encountered.

This short-circuit behavior leaks information through execution time. An attacker who can send many authentication attempts and measure response latency can determine, byte by byte, how much of a candidate value matches the expected secret. Given enough samples to average out network jitter, the attacker can reconstruct client proofs or server signatures without ever knowing the underlying password. The impact is confidentiality of authentication material; integrity and availability are unaffected.

Root Cause

The root cause is the use of a non-constant-time comparison routine on secret data. Arrays.equals(byte[], byte[]) iterates from index zero and returns false at the first mismatch. When one operand is attacker-controlled and the other is a server-side secret, comparison time becomes a proxy for the length of the matching prefix, satisfying the classic precondition for a timing side-channel attack.

Attack Vector

Exploitation requires network access to an endpoint that performs SCRAM authentication using the vulnerable library. The attacker submits repeated authentication attempts with crafted proof values and measures response times. By varying candidate bytes and observing which choice produces a longer comparison, the attacker deduces the correct byte and moves to the next position. No user interaction or prior privileges are required.

java

// Patch from ongres/scram commit e0b0cf9
// ScramFunctions.java
 
 import static java.nio.charset.StandardCharsets.UTF_8;
 
+import java.security.MessageDigest;
 import java.security.SecureRandom;
-import java.util.Arrays;
 
 import com.ongres.scram.common.util.Preconditions;
 import org.jetbrains.annotations.NotNull;

The fix replaces Arrays.equals with MessageDigest.isEqual, which performs a constant-time comparison independent of matching prefix length. Source: ongres/scram commit e0b0cf9.

Detection Methods for CVE-2025-59432

Indicators of Compromise

Unusually high volumes of failed SCRAM authentication attempts from a single client or narrow source range, indicating timing measurement activity
Repeated authentication requests with subtly varying proof or signature byte values against the same account
Elevated authentication latency variance logged by services embedding the ongres/scram library

Detection Strategies

Inventory Java applications and dependency trees for com.ongres.scram artifacts with versions prior to 3.2 using software composition analysis tooling
Inspect authentication logs for accounts receiving hundreds or thousands of failed SCRAM proofs in short windows, which is atypical for legitimate clients
Correlate application logs with network telemetry to spot iterative probing patterns consistent with side-channel measurement

Monitoring Recommendations

Alert on authentication failure rate thresholds per source IP and per account for services using SCRAM
Track dependency versions in CI/CD pipelines and fail builds that pull vulnerable ongres/scram releases
Enable audit logging on database and messaging services that use SCRAM to capture proof-verification failures

How to Mitigate CVE-2025-59432

Immediate Actions Required

Upgrade the ongres/scram library to version 3.2 or later in all Java applications performing SCRAM authentication
Rebuild and redeploy downstream artifacts, containers, and services that transitively depend on the vulnerable library
Rotate credentials for accounts that may have been targeted by repeated SCRAM authentication probing

Patch Information

The maintainers patched the issue by replacing Arrays.equals with MessageDigest.isEqual for secret comparisons. Details are published in GitHub Security Advisory GHSA-3wfh-36rx-9537 and the fix commit is available at ongres/scram commit e0b0cf9. For background on constant-time comparison, see the Oracle MessageDigest.isEqual documentation.

Workarounds

Rate-limit SCRAM authentication attempts per source IP and per account to reduce the number of timing samples an attacker can collect
Front SCRAM-authenticated services with network controls that block clients producing abnormal volumes of failed authentications
Where feasible, temporarily disable SCRAM in favor of TLS client certificates until the library upgrade is deployed

bash

# Example: pin a non-vulnerable version in Maven
# pom.xml dependency override
# <dependency>
#   <groupId>com.ongres.scram</groupId>
#   <artifactId>scram-client</artifactId>
#   <version>3.2</version>
# </dependency>

mvn dependency:tree | grep ongres.scram
mvn versions:use-dep-version -Dincludes=com.ongres.scram:scram-client -DdepVersion=3.2 -DforceVersion=true