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

> Attackers can cause denial of service by supplying unbounded iteration counts in PKCS#12 or PBES1 parameters, forcing excessive computation during key derivation.

- **Severity:** Medium 5.3 (`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`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 3 Oct 2026
- **Updated:** 5 Oct 2026
- **Also known as:** CLEANSTART-2026-MT03489, CLEANSTART-2026-TA59206, DEBIAN-CVE-2026-97873, GHSA-78x9-mjv2-rr3v, UBUNTU-CVE-2026-97873

## What is CVE-2026-97873?

CVE-2026-97873 is a medium-severity denial of service vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA, published on 3 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-770 (Allocation of Resources Without Limits or Throttling)

## Which versions are affected by CVE-2026-97873?


## How do I fix CVE-2026-97873?

Upgrade to a fixed version.

## Is CVE-2026-97873 being exploited?

There is no known exploitation of CVE-2026-97873 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-97873 and fix it if it is affected.

What it is: CVE-2026-97873 is a medium-severity denial of service vulnerability in Legion of the Bouncy Castle Inc. BC-JAVA, published on 3 Oct 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-97873 in the wild and no public exploit code.

Affected product: Legion of the Bouncy Castle Inc. BC-JAVA. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-97873/ (Markdown: https://insights.sbomify.com/CVE-2026-97873/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-97873
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-97873
- OSV: https://osv.dev/vulnerability/CVE-2026-97873

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From sbomify Insights: https://insights.sbomify.com/CVE-2026-97873/
Summaries are generated and may contain mistakes; the official description above is the record.