CVE-2026-8149 PUBLISHED

GCM chunking can lead to bad tag exception on decryption

Assigner: bcorg
Reserved: 08.05.2026 Published: 08.05.2026 Updated: 08.05.2026

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.

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/S:N/RE:M/U:Amber
CVSS Score: 5.1

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Local	Confidentiality	None	Confidentiality	None
Attack Complexity	Low	Integrity	None	Integrity	None
Attack Requirements	None	Availability	Low	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

Vendor	Legion of the Bouncy Castle Inc.
Product	BC-FJA
Versions	Default: unaffected affected from 2.1.0 to 2.1.2 (incl.)

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