High 8.7Published Oct 2, 2026

CVE-2026-63574Unbounded allocation from OpenPGP signature and user attribute subpacket lengths

Updated under an hour ago (2026-10-19 13:10 UTC)

Does this affect you?

It affects Legion of the Bouncy Castle Inc. bc-csharp. Add what you run to find out whether that includes you.

EPSS puts the chance of exploitation in the next 30 days at 0.32%, higher than 23% of scored CVEs.

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Every CVE for Legion of the Bouncy Castle Inc. bc-csharp

Exploited in the last 30 days

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: 8.7 HIGH (v4.0, CNA)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
Weakness (CWE): CWE-789
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): 0.32% (percentile 23)
Assigned by: bcorg
NVD analysis: Undergoing Analysis
Record last updated: Oct 2, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Legion of the Bouncy Castle Inc. bc-csharp legion_of_the_bouncy_castle:bc_csharp (from the name)	before 2.7.0	CNA record

References

https://github.com/bcgit/bc-csharp/wiki/CVE-2026-63574vendor-advisory
https://github.com/bcgit/bc-csharp/commit/f51dacf4817d9ea10d0a9841f72fac3655c65483patch
https://github.com/bcgit/bc-csharp/commit/986fb4892bb39f292ba0fd82eba11d2cbc503217patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.