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CVE-2026-97873— Legacy PBES1 and PKCS#12 PBE iteration count honoured unbounded in the raw JCA provider

Quick assessment

Affected
Legion of the Bouncy Castle Inc. BC-JAVA
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.

在 Bouncy Castle for Java 1.86 之前的版本中，原生 JCA 提供程序对传统 PBES1（PKCS#5 方案 1）和 PKCS#12 PBE 密码族在基于密码的密钥派生过程中，所使用的迭代次数直接从不可信输入中获取，且未进行上限限制。因此，攻击者可以通过提供极小的输入值，迫使系统在验证任何内容之前执行任意数量的计算工作，从而导致拒绝服务（DoS）攻击。 PKCS12PBE 及其对象标识符别名以及 PBKDF1 的 AlgorithmParameters 实现允许接受来自编码后的 PKCS1

CVSS 5.3 · Medium
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I. Basic Information for CVE-2026-97873

Vulnerability Information
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Vulnerability Title
Legacy PBES1 and PKCS#12 PBE iteration count honoured unbounded in the raw JCA provider
Source: CVE Program / CVE List V5
Vulnerability Description
In Bouncy Castle for Java before 1.86, the raw JCA provider's legacy PBES1 (PKCS#5 scheme 1) and PKCS#12 PBE families ran their password-based key derivation with an iteration count taken from untrusted input without bounding it, so a small input could dictate an arbitrary amount of work before anything could be verified. The AlgorithmParameters implementations (PKCS12PBE and its object identifier aliases, and PBKDF1) accepted any count from an encoded PKCS12PBEParams or PBEParameter, narrowing a value beyond the int range with intValue(), and every Cipher, Mac and SecretKeyFactory in these families derived with whatever count it was given, including one decoded by another provider's AlgorithmParameters, as when javax.crypto.EncryptedPrivateKeyInfo.getKeySpec() decrypts a PKCS#12 PBE-protected private key with BC. Both the parameter parse and the derivations now reject a negative or over-limit count under the org.bouncycastle.pbe.max_iteration_count property (default 10,000,000) that already bounded PBKDF2 (CVE-2026-17508), and the parse rejects a count beyond the int range rather than narrowing it. This issue also affects Bouncy Castle for Java LTS before 2.73.13.
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:L/SC:N/SI:N/SA:N/U:Amber
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-JAVA 0 ~ 1.86 -
Legion of the Bouncy Castle Inc. BC-LTS-JAVA 2.73.0 ~ 2.73.13 -

II. Public POCs for CVE-2026-97873

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III. Intelligence Information for CVE-2026-97873

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Patches & Fixes for CVE-2026-97873 (1)

Other References for CVE-2026-97873 (1)

Same Patch Batch · Legion of the Bouncy Castle Inc. · 2026-10-03 · 12 CVEs total

CVE-2026-71885 9.2 CRITICAL MLS X.509 credential not bound to the LeafNode signature key
CVE-2026-71888 8.7 HIGH CMS AuthenticatedData exposes attacker-inserted authAttrs when digestAlgorithm is absent
CVE-2026-71889 8.7 HIGH PKIXCertPathReviewer does not apply X.509 name constraints to the target certificate
CVE-2026-71890 8.7 HIGH MLS external commit can remove an arbitrary group member
CVE-2026-85515 8.2 HIGH OpenPGP message truncation not reported, bypassing the SEIPDv1 integrity check
CVE-2026-71887 8.2 HIGH OpenPGP data signature accepted from a signing subkey without cross-certification
CVE-2026-71883 8.2 HIGH Native AES packet cipher returns the raw AES key on an alias
CVE-2026-71886 8.2 HIGH OpenPGP certification accepted from a subkey without certification authority
CVE-2026-71891 7.1 HIGH BLS12-381 key validation accepts a public key built on a foreign curve
CVE-2026-71892 6.9 MEDIUM CMS key-transport recipient key-size validation never runs for RFC 9709 HKDF-derived keys
CVE-2026-18040 5.9 MEDIUM HQC leaks private key information through secret-indexed GF(2^8) tables and a secret-depen

IV. Related Vulnerabilities

Same product: BC-JAVA
Same vendor: Legion of the Bouncy Castle Inc.
Same weakness: CWE-770

V. Comments for CVE-2026-97873

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