CVE-2026-119078

Received Received - Intake

Blake3 Key Derivation Issue in Apache Commons Codec

Publication date: 2026-11-09

Last updated on: 2026-11-09

Assigner: Apache Software Foundation

Description

Apache Commons Codec's Blake3 class documented the output of its doFinalize methods as depending on any previously finalized bytes, so that consecutive calls would return different output. In fact, doFinalize does not change the hash state: calling it again without supplying more input returns the same bytes. The key-derivation example in the class Javadoc, shipped since 1.16.0, derives two keys with two consecutive doFinalize calls. Code that follows it gets identical keys, so the separation between the derived keys is lost. The same applies to any application that calls doFinalize more than once on one instance and expects new output each time. This issue affects Apache Commons Codec from 1.16.0 before 1.23.0. Version 1.23.0 corrects the documentation, but the behavior of doFinalize is unchanged. Upgrading alone does not fix affected code. Users should check their applications for repeated doFinalize calls on the same Blake3 instance and derive multiple keys by requesting the combined length in one call and splitting the output, as the updated Javadoc shows.

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Meta Information

Published

2026-11-09

Last Modified

2026-11-09

Generated

2026-11-10

AI Q&A

2026-11-10

EPSS Evaluated

N/A

NVD

CVE-2026-119078

EUVD

EUVD-2026-120400

Affected Vendors & Products

Vendor	Product	Version / Range
Apache Software Foundation	Apache Commons Codec	From 1.16.0 (inc) to 1.23.0 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-1068	The implementation of the product is not consistent with the design as described within the relevant documentation.
CWE-684	The code does not function according to its published specifications, potentially leading to incorrect usage.

Attack-Flow Graph

Executive Summary

This vulnerability affects Apache Commons Codec's Blake3 class. The doFinalize method was incorrectly documented to produce different output on consecutive calls, but it actually returns the same bytes each time without changing the hash state. This means applications calling doFinalize multiple times expecting new output will receive identical results, breaking key separation in cryptographic operations.

Detection Guidance

Detecting this vulnerability requires checking if your application uses Apache Commons Codec 1.16.0 to 1.22.0 and calls doFinalize multiple times on the same Blake3 instance. Review application code for repeated doFinalize calls without new input. No specific commands are provided for detection.

Impact Analysis

If your application uses Apache Commons Codec 1.16.0 to 1.22.0 and calls doFinalize multiple times on the same Blake3 instance, you may derive identical cryptographic keys instead of distinct ones. This could weaken security by allowing unauthorized access if keys are reused or predictable.

Compliance Impact

This vulnerability may violate compliance requirements for cryptographic key generation in GDPR (data protection) and HIPAA (health data security). Weak or predictable keys could lead to unauthorized data access, failing security controls mandated by these regulations.

Mitigation Strategies

Upgrade Apache Commons Codec to version 1.23.0 or later. Additionally, review and modify application code to avoid calling doFinalize multiple times on the same Blake3 instance. Derive multiple keys by requesting combined length in one call and splitting the output.

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