CVE-2026-63574

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.

Is your site exposed to CVE-2026-63574?

Run a free security scan — no signup, results in seconds.

EPSS — Exploit Prediction

0.0032

Probability of exploitation

0.22%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-789 CWE-789

References

Other References

https://github.com/bcgit/bc-csharp/commit/986fb4892bb39f292ba0fd82eba11d2cbc503217 https://github.com/bcgit/bc-csharp/commit/f51dacf4817d9ea10d0a9841f72fac3655c65483 https://github.com/bcgit/bc-csharp/wiki/CVE-2026-63574

Frequently Asked Questions

What is 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.

How do I check if I'm vulnerable to CVE-2026-63574? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-12185

In Bouncy Castle for Java before 1.85, BKS/UBER keystore allocates from untrusted lengths before integrity check. This issue also affects …

CVE-2026-58060

In Bouncy Castle for Java before 1.85, HSS public-key level count unbounded, enabling huge allocation on verify. This issue also …

CVE-2026-12852

In Bouncy Castle for Java before 1.85, MLS wire decoder allocates attacker-declared opaque length before bounds check.

CVE-2026-14682

In Bouncy Castle for Java before 1.85, Possible OOM from unbounded up-front allocation on a definite-length read. This issue also …

CVE-2026-19204

A client may send a WebSocket frame with an unknown opcode and a very large declared payload length, causing Jetty …

CVE-2025-26618

Erlang is a programming language and runtime system for building massively scalable soft real-time systems with requirements on high availability. …