{
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    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-103601",
        "assignerOrgId": "91579145-5d7b-4cc5-b925-a0262ff19630",
        "state": "PUBLISHED",
        "assignerShortName": "bcorg",
        "dateReserved": "2026-09-30T23:01:10.053Z",
        "datePublished": "2026-10-02T07:09:17.064Z",
        "dateUpdated": "2026-10-02T17:52:45.900Z"
    },
    "containers": {
        "cna": {
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                "orgId": "91579145-5d7b-4cc5-b925-a0262ff19630",
                "shortName": "bcorg",
                "dateUpdated": "2026-10-02T07:09:17.064Z"
            },
            "title": "CcmBlockCipher and KCcmBlockCipher leave unverified plaintext in the output buffer after a failed tag check",
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "lang": "en",
                            "cweId": "CWE-354",
                            "description": "CWE-354 Improper Validation of Integrity Check Value",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "impacts": [
                {
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                        {
                            "lang": "en",
                            "value": "Confidentiality (unverified plaintext left in the caller's buffer after a failed tag check, giving a CTR decryption oracle)"
                        }
                    ]
                }
            ],
            "affected": [
                {
                    "vendor": "Legion of the Bouncy Castle Inc.",
                    "product": "bc-csharp",
                    "collectionURL": "https://www.nuget.org/packages/BouncyCastle.Cryptography",
                    "packageName": "BouncyCastle.Cryptography",
                    "repo": "https://github.com/bcgit/bc-csharp",
                    "programFiles": [
                        "crypto/src/crypto/modes/CcmBlockCipher.cs",
                        "crypto/src/crypto/modes/KCcmBlockCipher.cs"
                    ],
                    "versions": [
                        {
                            "status": "affected",
                            "version": "0",
                            "lessThan": "2.7.0",
                            "versionType": "semver"
                        }
                    ],
                    "defaultStatus": "unaffected"
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            ],
            "descriptions": [
                {
                    "lang": "en",
                    "value": "Release of unverified plaintext in the CCM (CcmBlockCipher) and DSTU 7624 CCM (KCcmBlockCipher) AEAD modes in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote attacker to obtain decryptions of ciphertexts of their choosing via forged messages sent to an application that lets the output buffer of a failed decryption be observed, for example through buffer reuse or logging, because decryption wrote the recovered plaintext into the caller-supplied output buffer before checking the authentication tag and left it there when the check failed. Only decryption into a caller-supplied buffer is affected; methods that return a newly allocated array are not.",
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                            "value": "Release of unverified plaintext in the CCM (CcmBlockCipher) and DSTU 7624 CCM (KCcmBlockCipher) AEAD modes in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote attacker to obtain decryptions of ciphertexts of their choosing via forged messages sent to an application that lets the output buffer of a failed decryption be observed, for example through buffer reuse or logging, because decryption wrote the recovered plaintext into the caller-supplied output buffer before checking the authentication tag and left it there when the check failed. Only decryption into a caller-supplied buffer is affected; methods that return a newly allocated array are not."
                        }
                    ]
                }
            ],
            "references": [
                {
                    "url": "https://github.com/bcgit/bc-csharp/wiki/CVE-2026-103601",
                    "tags": [
                        "vendor-advisory"
                    ]
                },
                {
                    "url": "https://github.com/bcgit/bc-csharp/commit/e0868323645a063cb2479646e93c1449dc338de5",
                    "tags": [
                        "patch"
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                },
                {
                    "url": "https://github.com/bcgit/bc-csharp/commit/4ddb1d0bfeae3a81b18f4446d8cc8a7871bd2d9f",
                    "tags": [
                        "patch"
                    ]
                }
            ],
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                    "format": "CVSS",
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "GENERAL"
                        }
                    ],
                    "cvssV4_0": {
                        "attackVector": "NETWORK",
                        "attackComplexity": "LOW",
                        "attackRequirements": "PRESENT",
                        "privilegesRequired": "NONE",
                        "userInteraction": "NONE",
                        "vulnConfidentialityImpact": "HIGH",
                        "subConfidentialityImpact": "NONE",
                        "vulnIntegrityImpact": "NONE",
                        "subIntegrityImpact": "NONE",
                        "vulnAvailabilityImpact": "NONE",
                        "subAvailabilityImpact": "NONE",
                        "exploitMaturity": "NOT_DEFINED",
                        "Safety": "NOT_DEFINED",
                        "Automatable": "NOT_DEFINED",
                        "Recovery": "NOT_DEFINED",
                        "valueDensity": "NOT_DEFINED",
                        "vulnerabilityResponseEffort": "NOT_DEFINED",
                        "providerUrgency": "NOT_DEFINED",
                        "version": "4.0",
                        "baseSeverity": "HIGH",
                        "baseScore": 8.2,
                        "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N"
                    }
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "value": "Discovered by Claude, Anthropic's AI assistant, and triaged by the Anthropic security team in collaboration with Anthropic Research.",
                    "type": "finder"
                }
            ],
            "source": {
                "discovery": "EXTERNAL"
            },
            "x_generator": {
                "engine": "Claude Opus 5.5"
            },
            "x_antReportIds": [
                "ANT-2026-A41MAVE2"
            ]
        },
        "adp": [
            {
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-10-02T17:50:08.465930Z",
                                "id": "CVE-2026-103601",
                                "options": [
                                    {
                                        "Exploitation": "none"
                                    },
                                    {
                                        "Automatable": "no"
                                    },
                                    {
                                        "Technical Impact": "partial"
                                    }
                                ],
                                "role": "CISA Coordinator",
                                "version": "2.0.3"
                            }
                        }
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                ],
                "title": "CISA ADP Vulnrichment",
                "providerMetadata": {
                    "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-10-02T17:52:45.900Z"
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