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.
Published: 2026-11-09
Score: n/a
EPSS: n/a
KEV: No
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History

Mon, 09 Nov 2026 20:15:00 +0000

Type Values Removed Values Added
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.
Title Apache Commons Codec: Blake3 doFinalize is stateless; the documented KDF example derives identical keys
Weaknesses CWE-1068
CWE-684
References

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cve-icon MITRE

Status: PUBLISHED

Assigner: apache

Published:

Updated: 2026-11-09T20:11:12.230Z

Reserved: 2026-10-29T13:10:03.787Z

Link: CVE-2026-119078

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-11-09T20:18:04.697

Modified: 2026-11-09T20:18:04.697

Link: CVE-2026-119078

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-11-09T21:30:11Z

Weaknesses