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CVE-2026-103603

Unbounded HSS public key level count allows huge array allocation during signature verification PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / productVersions
Legion of the Bouncy Castle Inc. / bc-csharpaffected 0 before 2.7.0

CWE

CWE-789

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.