CVE-2026-8149

GCM chunking can lead to bad tag exception on decryption

Published May 8, 2026 CVSS 4.0 · 5.1 Medium EPSS < 1% KEV · Not listed
Description
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.

Remediation

Vendor Workaround

If possible pass whole message to GCM via doFinal(..) for decryption. Issue only occurs when decryption is chunked at certain boundaries.

Tracking

Sign in to view the affected projects.

Advisories

Source ID Title
Github GHSA Github GHSA GHSA-mx76-r943-rf8g Bouncy Castle LTS native GCM chunking can cause bad-tag exception on decryption
History
Type Values Removed Values Added
Description A vulnerability in Legion of the Bouncy Castle Inc. BC-LTS on Linux, X86_64, AVX, AVX-512f. This vulnerability is associated with program files gcm128w, gcm512w. This issue affects BC-LTS: from 2.73.0 before 2.73.11. 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.
Type Values Removed Values Added
Description A vulnerability in Legion of the Bouncy Castle Inc. BC-LTS on Linux, X86_64, AVX, AVX-512f. This vulnerability is associated with program files gcm128w, gcm512w. This issue affects BC-LTS: from 2.73.0 through 2.73.10. A vulnerability in Legion of the Bouncy Castle Inc. BC-LTS on Linux, X86_64, AVX, AVX-512f. This vulnerability is associated with program files gcm128w, gcm512w. This issue affects BC-LTS: from 2.73.0 before 2.73.11.
References
Type Values Removed Values Added
Description A vulnerability in 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. This issue affects BC-FJA: from 2.1.0 through 2.1.2. A vulnerability in Legion of the Bouncy Castle Inc. BC-LTS on Linux, X86_64, AVX, AVX-512f. This vulnerability is associated with program files gcm128w, gcm512w. This issue affects BC-LTS: from 2.73.0 through 2.73.10.
Type Values Removed Values Added
First Time appeared Bouncycastle
Bouncycastle bc-fja
Vendors & Products Bouncycastle
Bouncycastle bc-fja
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description A vulnerability in 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. This issue affects BC-FJA: from 2.1.0 through 2.1.2.
Title GCM chunking can lead to bad tag exception on decryption
Weaknesses CWE-1068
References
Metrics cvssV4_0

{'score': 5.1, '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/S:N/RE:M/U:Amber'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
bcorg
Published
Updated
Jul 21, 2026, 4:59 AM
Reserved
May 8, 2026, 5:23 AM
Status
Awaiting Analysis
Published
May 8, 2026, 7:16 AM
Modified
Oct 26, 2026, 7:10 PM