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

Quick assessment

Affected
Legion of the Bouncy Castle Inc. bc-csharp
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

PKCS#12 密钥库加载过程中资源分配缺乏限制（Pkcs12Store.Load）在 Legion of the Bouncy Castle Inc. 发布的 bc-csharp 库 2.7.0 版本之前存在安全漏洞。攻击者通过提供精心构造的 PKCS#12（PFX）文件，可导致拒绝服务攻击。具体而言，攻击者可将文件中的 MacData 或加密 SafeContents/shrouded key bag 的 PBE（基于密码的加密）参数中的迭代次数设置为接近 2^31 的值。由于系统从文件中直接读取该迭代次数而未

CVSS 7.1 · High

Possible ATT&CK Techniques 1 AI

T1496 · Resource Hijacking
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I. Basic Information for CVE-2026-63572

Vulnerability Information
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Vulnerability Title
Unbounded MAC and bag-decryption iteration counts when loading PKCS#12 files
Source: CVE Program / CVE List V5
Vulnerability 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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
不加限制或调节的资源分配
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Legion of the Bouncy Castle Inc. bc-csharp 0 ~ 2.7.0 -

II. Public POCs for CVE-2026-63572

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III. Intelligence Information for CVE-2026-63572

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Other References for CVE-2026-63572 (5)

Same Patch Batch · Legion of the Bouncy Castle Inc. · 2026-10-02 · 24 CVEs total

CVE-2026-63569 9.1 CRITICAL MTI/A0 DHAgreement does not validate the peer's ephemeral value
CVE-2026-63571 8.7 HIGH Attribute certificate path validation does not verify the attribute certificate's signatur
CVE-2026-63566 8.7 HIGH DTLS handshake reassembler allocates buffer from unchecked 24-bit length
CVE-2026-63574 8.7 HIGH Unbounded allocation from OpenPGP signature and user attribute subpacket lengths
CVE-2026-63568 8.7 HIGH Unbounded CMP/CRMF password-based MAC iteration count allows CPU exhaustion
CVE-2026-103600 8.7 HIGH Unbounded ASN.1 nesting depth causes process-terminating stack overflow
CVE-2026-103604 8.7 HIGH Quadratic-time escaping when converting X.509 distinguished names to strings
CVE-2026-103603 8.7 HIGH Unbounded HSS public key level count allows huge array allocation during signature verific
CVE-2026-16000 8.7 HIGH KCcmBlockCipher (DSTU 7624 CCM) tag not bound to nonce when no associated data is used
CVE-2026-17507 8.7 HIGH MLS membership checks compare a uint32 leaf_index as signed, admitting an out-of-range sen
CVE-2026-103602 8.2 HIGH Name constraints bypass via trailing dot in rfc822Name, dNSName and URI hosts
CVE-2026-18036 8.2 HIGH NTRU leaks private key information by reducing secret values with a non-constant-time inte
CVE-2026-63577 8.2 HIGH Name Constraints bypass: directoryName constraint matched at any position in the DN instea
CVE-2026-63576 8.2 HIGH URI name constraints checked against a mis-parsed host
CVE-2026-63573 8.2 HIGH Bleichenbacher padding oracle in CMS RSA PKCS#1 v1.5 key-transport unwrap
CVE-2026-103601 8.2 HIGH CcmBlockCipher and KCcmBlockCipher leave unverified plaintext in the output buffer after a
CVE-2026-63567 8.2 HIGH IesEngine block-cipher mode checks padding before MAC (CBC padding oracle)
CVE-2026-15999 8.2 HIGH AES-CCM decryption accepts zero or out-of-range tag length, bypassing authentication
CVE-2026-16001 8.2 HIGH IesEngine stream-mode MAC forgery via length-dependent KDF split
CVE-2026-63578 7.1 HIGH Unbounded PBE iteration count when decrypting PKCS#8 private keys

Showing top 20 of 24 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

Same product: bc-csharp
Same vendor: Legion of the Bouncy Castle Inc.
Same weakness: CWE-770

V. Comments for CVE-2026-63572

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