Unauthenticated decryption oracle via late tag validation
Published Aug 3, 2026 · Updated Aug 3, 2026
Improper tag validation in Bouncy Castle Java, LTS, and FIPS allows attackers to obtain unauthenticated CCM decryption output. In affected releases, CCMBlockCipher.processPacket and equivalent KCCMBlockCipher and KGCMBlockCipher paths write decrypted bytes to the caller buffer before authenticating the tag, and failure handling does not clear the buffer. Exploitation requires forged ciphertext input plus visibility into the failed-call buffer through reuse, logging, or memory inspection; affected versions are before 1.85, LTS before 2.73.12, and FIPS before 1.0.2.7 in 1.0.X, before 2.0.2 in 2.0.X, and before 2.1.3 in 2.1.X.
Summary
What happened
Improper tag validation in Bouncy Castle Java, LTS, and FIPS allows attackers to obtain unauthenticated CCM decryption output. In affected releases, CCMBlockCipher.processPacket and equivalent KCCMBlockCipher and KGCMBlockCipher paths write decrypted bytes to the caller buffer before authenticating the tag, and failure handling does not clear the buffer. Exploitation requires forged ciphertext input plus visibility into the failed-call buffer through reuse, logging, or memory inspection; affected versions are before 1.85, LTS before 2.73.12, and FIPS before 1.0.2.7 in 1.0.X, before 2.0.2 in 2.0.X, and before 2.1.3 in 2.1.X.
The record
- CVE
- CVE-2026-58061
- Published
- Aug 3, 2026
- Updated
- Aug 3, 2026
- Vendor
- Legion of the Bouncy Castle Inc.
- Product
- Bouncy Castle Java
- Classifications
- CWE-354
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Aug 3, 2026CVE publishedPublication date reported by the CVE source.
- Aug 3, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=0 <1.85
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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