What’s Vulnerable › Vulnerabilities

CVE-2026-63572: Unbounded MAC and bag-decryption iteration counts when loading PKCS#12 files

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-02 · updated 2026-10-28
• Weakness: CWE-770

Description

Allocation of resources without limits in PKCS#12 keystore loading (Pkcs12Store.Load) in Legion of the Bouncy Castle Inc. bc-csharp before 2.7.0 allows an attacker who can supply a PKCS#12 (PFX) file to cause a denial of service through CPU exhaustion via an iteration count close to 2^31 in the file's MacData or in the PBE parameters of an encrypted SafeContents or shrouded key bag, because the counts are taken from the file without an upper bound and the key derivation runs before the MAC or the password can be checked. A zero or negative count is covered by CVE-2026-63575. Pkcs12Utilities.ConvertToDefiniteLength is also affected.

Affected products

• Legion of the Bouncy Castle Inc. bc-csharp: before 2.7.0 — fixed in 2.7.0
• Legion of the Bouncy Castle Inc. bc-csharp: before 2.7.0 — fixed in 2.7.0

How to fix

Upgrade to a fixed version: Legion of the Bouncy Castle Inc. bc-csharp 2.7.0; Legion of the Bouncy Castle Inc. bc-csharp 2.7.0. Check the vendor advisory for mitigations.

References

• https://github.com/bcgit/bc-csharp/commit/34a7c05f719c91c024f285c6b420d3c00f8019dd
• https://github.com/bcgit/bc-csharp/commit/54ea0b179ee627027829b44c45d6dd32e575bd67
• https://github.com/bcgit/bc-csharp/commit/7c0ed15f9783c9595b1a53f3900136461fd944f4
• https://github.com/bcgit/bc-csharp/commit/b57165ecb7790ecea08273b219d52d80c12990e4
• https://github.com/bcgit/bc-csharp/commit/c00fc018fca89c077c64dd2a2a2eb00ae7d97241
• https://github.com/bcgit/bc-csharp/wiki/CVE-2026-63572

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