CVE-2026-15997: Native ARM SHA3 / SHAKE `restoreFullState` fails to detect size_t underflow in a crafted encoded state

Severity: low (CVSS 1.7 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-16 · updated 2026-10-24
Weakness: CWE-787

Description

Out-of-bounds write vulnerability in Legion of the Bouncy Castle Inc. BC-LTS bcprov-lts8on on ARM allows Overflow Buffers. This vulnerability is associated with program files https://github.Com/bcgit/bc-lts-java/blob/main/native_c/arm/sha/shake.C, https://github.Com/bcgit/bc-lts-java/blob/main/native_c/arm/sha/sha3.C. This issue affects BC-LTS: from 2.73.0 before 2.73.12.1. Issue is only applicable if application involved is accepting memoable SHA3 / SHAKE states from potentially untrusted sources.

Affected products

Legion of the Bouncy Castle Inc. BC-LTS: from 2.73.0 before 2.73.12.1 — fixed in 2.73.12.1

How to fix

Upgrade to a fixed version: Legion of the Bouncy Castle Inc. BC-LTS 2.73.12.1. Check the vendor advisory for mitigations.

References

https://github.com/bcgit/bc-lts-java/wiki/CVE-2026-15997

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