CVE-2026-103603High· 8.7▾ TwilightMemory allocation with excessive size value in the HSS/LMS signature code (HssPublicKeyParameters, HssSignature) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote unauthenticated attacker who can supply both an H…
▾ Twilight zone — High severity, or a signal on a lesser flaw
impact 47.8 · likelihood 0 · exploitation 0
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Memory allocation with excessive size value in the HSS/LMS signature code (HssPublicKeyParameters, HssSignature) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows a remote unauthenticated attacker who can supply both an HSS public key and a signature to cause a denial of service through memory exhaustion via a public key encoding with an excessive level count, because the level count L read when parsing an HSS public key was not checked against the RFC 8554 maximum of 8, and signature parsing then allocated an array of L - 1 entries before reading any further signature data. A single verification can commit up to about 17 GB of memory or fail with an OutOfMemoryException.
Refer to the linked advisories for vendor-supplied fixes and affected version ranges.
Connected by shared product, vendor, weakness, or advisory.
CVE-2026-63574High· 8.7Memory allocation with excessive size value in the OpenPGP signature and user attribute subpacket parsers (SignatureSubpacketsParser.ReadPacket, UserAttributeSubpacketsParser.ReadPacket) in Legion of the Bouncy Castle Inc
CVE-2026-63566High· 8.7Memory allocation with excessive size value in the DTLS handshake reassembly (DtlsReliableHandshake, DtlsReassembler) in Legion of the Bouncy Castle Inc
CVE-2026-63570High· 7.1Loop with unreachable exit condition in Pkcs12Store.GetCertificateChain in Legion of the Bouncy Castle Inc
CVE-2026-63571High· 8.7Improper verification of cryptographic signature in the attribute certificate path validator (PkixAttrCertPathValidator, also used by PkixAttrCertPathBuilder) in Legion of the Bouncy Castle Inc
CVE-2026-63572High· 7.1Allocation of resources without limits in PKCS#12 keystore loading (Pkcs12Store.Load) in Legion of the Bouncy Castle Inc
CVE-2026-63573High· 8.2Observable discrepancy in the CMS RSA PKCS#1 v1.5 key-transport unwrap (KeyTransRecipientInformation.UnwrapKey) in Legion of the Bouncy Castle Inc