Buffer Handling Flaw in Bouncy Castle for Java Affects Multiple Versions
CVE-2026-58061

8.7HIGH

Key Information:

Vendor

Legion Of The Bouncy Castle Inc.

Status
Bc-java
Bc-lts-java
Bc-fja
Vendor
CVE Published:
3 August 2026

What is CVE-2026-58061?

A vulnerability has been identified in Bouncy Castle for Java prior to version 1.85, where CCM-family modes allow plaintext to be written to the caller's buffer before performing a tag check. This potentially exposes sensitive data in cases where the integrity of the data could not be confirmed. The issue extends to Bouncy Castle for Java LTS (long-term support) and FIPS versions, thus affecting a wide range of users and applications relying on this cryptographic toolkit.

Affected Version(s)

BC-FJA all 1.0.0 < 1.0.2.7

BC-FJA all 2.0.0 < 2.0.2

BC-FJA all 2.1.0 < 2.1.3

References

https://github.com/bcgit/bc-java/wiki/CVE%E2%80%902026%E2...
vendor-advisory
https://github.com/bcgit/bc-java/commit/cd4a5ab3ad619ff03...
patch
https://github.com/bcgit/bc-java/commit/08d675106bb663ddc...
patch

CVSS V4

Score:
8.7
Severity:
HIGH
Confidentiality:
None
Integrity:
High
Availability:
None
Attack Vector:
Network
Attack Complexity:
Low
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

Credit

Alex Gaynor in collaboration with Claude and Anthropic Research
.