Legion of the Bouncy Castle bc-csharp up to 2.6.x OpenPGP Subpacket Parsers memory allocation

Summaryinfo

A vulnerability was found in Legion of the Bouncy Castle bc-csharp up to 2.6.x. It has been rated as problematic. Affected by this issue is the function SignatureSubpacketsParser.ReadPacket/UserAttributeSubpacketsParser.ReadPacket of the component OpenPGP Subpacket Parsers. Performing a manipulation results in memory allocation. This vulnerability is reported as CVE-2026-63574. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Legion of the Bouncy Castle bc-csharp up to 2.6.x. It has been classified as problematic. This affects the function SignatureSubpacketsParser.ReadPacket/UserAttributeSubpacketsParser.ReadPacket of the component OpenPGP Subpacket Parsers. The manipulation with an unknown input leads to a memory allocation vulnerability. CWE is classifying the issue as CWE-789. The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated. This is going to have an impact on availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-63574 since 07/17/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 2.7.0 eliminates this vulnerability.

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Productinfo

Vendor

• Legion of the Bouncy Castle

Name

• bc-csharp

Version

• 2.0
• 2.1
• 2.2
• 2.3
• 2.4
• 2.5
• 2.6

CPE 2.3info

• 🔒
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CPE 2.2info

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