Legion of the Bouncy Castle bc-csharp up to 2.6.x AES-CCM Implementation ParameterUtilities.GetCipherParameters integrity check

CVSS Meta Temp Score
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CTI Interest Score
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7.0$0-$5k0.86

Summaryinfo

A vulnerability has been found in Legion of the Bouncy Castle bc-csharp up to 2.6.x and classified as critical. This affects the function ParameterUtilities.GetCipherParameters of the component AES-CCM Implementation. This manipulation causes integrity check. This vulnerability is registered as CVE-2026-15999. Remote exploitation of the attack is possible. No exploit is available. The affected component should be upgraded.

Detailsinfo

A vulnerability classified as critical was found in Legion of the Bouncy Castle bc-csharp up to 2.6.x. Affected by this vulnerability is the function ParameterUtilities.GetCipherParameters of the component AES-CCM Implementation. The manipulation with an unknown input leads to a integrity check vulnerability. The CWE definition for the vulnerability is CWE-354. The product does not validate or incorrectly validates the integrity check values or "checksums" of a message. This may prevent it from detecting if the data has been modified or corrupted in transmission. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

Improper validation of integrity check value in the AES-CCM implementation (CcmParameters and CcmBlockCipher) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an on-path attacker to modify CCM-encrypted content without detection via an AlgorithmIdentifier whose CCMParameters declare an authentication tag (aes-ICVlen) of zero or another length outside the RFC 5084 set, because CcmParameters accepted any value and CcmBlockCipher validated the tag length only when encrypting, so decryption compared a zero-length or very short tag. Affected paths include ParameterUtilities.GetCipherParameters, used by CmsEnvelopedData and CmsEnvelopedDataParser for EnvelopedData encrypted with AES-CCM, and any caller passing an unchecked tag length to CcmBlockCipher for decryption.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-15999 since 07/17/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 2.7.0 eliminates this vulnerability.

The vulnerability is also documented in the vulnerability database at CERT Bund (WID-SEC-2026-3713). Be aware that VulDB is the high quality source for vulnerability data.

Affected

  • Open Source Bouncy Castle

Productinfo

Vendor

Name

Version

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 7.3
VulDB Meta Temp Score: 7.0

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Integrity check
CWE: CWE-354 / CWE-345
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: bc-csharp 2.7.0

Timelineinfo

07/17/2026 CVE reserved
10/02/2026 +77 days Advisory disclosed
10/02/2026 +0 days VulDB entry created
10/02/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: github.com
Status: Confirmed

CVE: CVE-2026-15999 (🔒)
GCVE (CVE): GCVE-0-2026-15999
GCVE (VulDB): GCVE-100-412975
CERT Bund: WID-SEC-2026-3713 - Bouncy Castle: Mehrere Schwachstellen

Entryinfo

Created: 10/02/2026 09:32
Updated: 10/02/2026 14:59
Changes: 10/02/2026 09:32 (68), 10/02/2026 14:59 (7)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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