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    CVE-2026-63574

    Memory 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. bc-csharp before 2.7.0 allows a remote, unauthenticated attacker who can supply a crafted OpenPGP public key, certificate or signature to cause a denial of service (OutOfMemoryException or memory exhaustion in the parsing process) via a subpacket header using the five-octet length form, because the declared length was used to size the subpacket buffer with no upper bound and without being compared with the size of the enclosing subpacket area or packet, so a few bytes of input could demand an allocation of up to about 2 GB before any subpacket data was read.

    Published:Oct 2, 2026
    Last Modified:Oct 28, 2026
    EPS:Oct 2, 2026
    EPSS Score:0.00374
    CVSS Score:7.5

    Affected Products

    Vendor
    Bouncycastle
    Product
    Bc-csharp
    Vendor
    Legion Of The Bouncy Castle Inc.
    Product
    Bc-csharp

    Exploits

    No exploit reference

    Common Attack Pattern Enumeration and Classification (CAPEC)

    No CAPEC recorded yet

    Related CVEs

    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High