Apache Commons Codec: Blake3 doFinalize is stateless; the documented KDF example derives identical keys

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-119078
StatePUBLISHED
Assignerapache
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-11-09 20:18:04 UTC
Updated2026-11-10 01:17:15 UTC
DescriptionApache 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.

Risk And Classification

Problem Types: CWE-684 | CWE-1068 | CWE-684 CWE-684 Incorrect Provision of Specified Functionality | CWE-1068 CWE-1068 Inconsistency Between Implementation and Documented Design

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Apache Software Foundation Apache Commons Codec affected 1.16.0 1.23.0 maven Not specified

References

ReferenceSourceLinkTags
www.openwall.com/lists/oss-security/2026/11/09/29 af854a3a-2127-422b-91ae-364da2661108 www.openwall.com
lists.apache.org/thread.html/ol71kdgopfxwlxgqmkd0jrfcw05wdq5z [email protected] lists.apache.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Claude Security (en)

CNA: Gary D. Gregory (en)

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