Vulnerability record · CVE-2026-63574 · published 2 October 2026
CVE-2026-63574: Bouncycastle bc-csharp vulnerability
Bouncycastle · Bc Csharp
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.
Description
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.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:
Affected products
1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.
References
Track CVE-2026-63574 inside VULONE
Watch it alongside the ransomware crews, C2 infrastructure and forum chatter that reference it, query it through the API and pull it into your SIEM over TAXII.
Related vulnerabilities
Same products first, then exploited flaws of the same weakness class.
Source: NIST National Vulnerability Database (record CVE-2026-63574), CISA KEV, FIRST EPSS (scores of 2026-11-14). This page is refreshed as NVD updates the record.
