CVE-2026-8149
GCM chunking can lead to bad tag exception on decryption
A vulnerability in Legion of the Bouncy Castle Inc. BC-LTS bcprov-lts8on on X86_64, AVX, AVX-512f, Linux, Legion of the Bouncy Castle Inc. BC-FJA bc-fips on Linux, X86_64, AVX, AVX-512f.
This vulnerability is associated with program files gcm128w, gcm512w, gcm128w.C, gcm512w.C.
This issue affects BC-LTS: from 2.73.0 before 2.73.11; BC-FJA: from 2.1.0 before 2.1.3.
Attack profile
How easy it is to exploit
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
GCM chunking can lead to bad tag exception on decryption
A vulnerability in Legion of the Bouncy Castle Inc. BC-LTS bcprov-lts8on on X86_64, AVX, AVX-512f, Linux, Legion of the Bouncy Castle Inc. BC-FJA bc-fips on Linux, X86_64, AVX, AVX-512f.
This vulnerability is associated with program files gcm128w, gcm512w, gcm128w.C, gcm512w.C.
This issue affects BC-LTS: from 2.73.0 before 2.73.11; BC-FJA: from 2.1.0 before 2.1.3.
- Record
CVE-2026-8149- CVSS 4.0
- 5.1 Medium
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/S:N/RE:M/U:Amber - Weakness
- CWE-1068
- Updated
- 2026-11-02
EUVDEUVD-2026-28534
A vulnerability in Legion of the Bouncy Castle Inc. BC-LTS bcprov-lts8on on X86_64, AVX, AVX-512f, Linux, Legion of the Bouncy Castle Inc. BC-FJA bc-fips on Linux, X86_64, AVX, AVX-512f.
This vulnerability is associated with program files gcm128w, gcm512w, gcm128w.C, gcm512w.C.
This issue affects BC-LTS: from 2.73.0 before 2.73.11; BC-FJA: from 2.1.0 before 2.1.3.
- Record
EUVD-2026-28534- CVSS 4.0
- 5.1 Medium
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/S:N/RE:M/U:Amber - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-mx76-r943-rf8g
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.
- Record
GHSA-mx76-r943-rf8g- CVSS 4.0
- 5.1 Medium
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-354, CWE-1068
- Updated
- 2026-11-02
NVD
A vulnerability in Legion of the Bouncy Castle Inc. BC-LTS bcprov-lts8on on X86_64, AVX, AVX-512f, Linux, Legion of the Bouncy Castle Inc. BC-FJA bc-fips on Linux, X86_64, AVX, AVX-512f.
This vulnerability is associated with program files gcm128w, gcm512w, gcm128w.C, gcm512w.C.
This issue affects BC-LTS: from 2.73.0 before 2.73.11; BC-FJA: from 2.1.0 before 2.1.3.
- Record
CVE-2026-8149- CVSS 4.0
- 5.1 Medium
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:N/AU:X/R:X/V:X/RE:M/U:Amber - Weakness
- CWE-1068
- Updated
- 2026-11-02
OSVGHSA-mx76-r943-rf8g
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.
- Record
GHSA-mx76-r943-rf8g- CVSS 4.0
- 5.1 Medium
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-1068, CWE-354
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
org.bouncycastle:bcprov-lts8onMaven |
2.73.0 to 2.73.10 | 2.73.11 |
org.bouncycastle:bcprov-lts8onMaven |
2.73.0 up to 2.73.11, plus listed versions 2.73.12.73.102.73.22.73.32.73.4 Show 5 moreShow less2.73.52.73.62.73.72.73.82.73.9 |
2.73.11 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-8149 is a medium vulnerability (CVSS 5.1) in Legion Of The Bouncy Castle Inc. Bc-fja, published May 8, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.16%, the 4th percentile. Fixed in org.bouncycastle:bcprov-lts8on 2.73.11.