CVE-2026-63572

Unbounded MAC and bag-decryption iteration counts when loading PKCS#12 files

HIGH
7.5
CVSS Score
Published: October 2, 2026 at 07:04 AM UTC
Updated: October 28, 2026 at 01:17 PM UTC
2 products affected across 2 vendorsBc CsharpBouncy Castle for C# (bc-csharp)

Using bc-csharp by Legion of the Bouncy Castle Inc.?

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Severity
HIGH7.5
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 2.7.0
Affected range stops below 2.7.0, so it looks safe — our inference, not a vendor statement

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-770

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