Bouncy Castle LTS native GCM chunking can cause bad-tag exception on decryption
In Bouncy Castle LTS for Java, the AES/GCM native implementation used on Intel CPUs with AES PAA instruction sets (AVX / VAES / VAESF variants) can intermittently produce an incorrect authentication tag verification result during decryption when the ciphertext is fed in via a mix of update() calls followed by doFinal(). It is possible to work around it by either using doFinal() only (as the BCJSSE does) or by configuring the module to run in pure Java mode, by setting the system property "org.bouncycastle.native.cpu_variant" to java.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Java / Kotlin (Maven) | org.bouncycastle:bcprov-lts8on | >= 2.73.0, < 2.73.11 | 2.73.11 |
References
- CVSS vector
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N- Weakness (CWE)
CWE-1068, CWE-354- Platform
- Java / Kotlin (Maven)
- Package
org.bouncycastle:bcprov-lts8on- Disclosed
- 08.05.2026
- Updated
- 11.10.2026 13:20
Sources and licenses
OSV / GitHub Advisory Database - GHSA-mx76-r943-rf8g - CC BY 4.0
Vulnerability history: org.bouncycastle:bcprov-lts8on
All published vulnerabilities of this package (Java / Kotlin (Maven)), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 4
- First → latest
- 05.2024 08.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- Critical 1
- High 1
- Medium 2
Disclosures per year
- 2024: 1
- 2025: 0
- 2026: 3
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Bouncy Castle LTS native GCM chunking can cause bad-tag exception on decryption this entry
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