# bcrypt-ruby has an Integer Overflow that Causes Zero Key-Strengthening Iterations at Cost=31 on JRuby

Advisory record · `GHSA-f27w-vcwj-c954`

- **Identifiers:** `GHSA-f27w-vcwj-c954` · `CVE-2026-33306`
- **State:** Confirmed
- **Severity:** CVSS 4.5 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-190](https://cwe.mitre.org/data/definitions/190.html)
- **Tags:** [Memory corruption](https://agentprime.io/advisories/tag/memory-corruption.md)
- **Published:** 19 Mar 2026
- **Updated:** 25 Mar 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 19 Mar 2026, 17:54 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `bcrypt` (RubyGems): affected `<3.1.22`; fixed in `3.1.22`

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 4.5 Medium, CVSS 4.0: `CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0024, the 14th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

This record came from the full history of the GitHub Advisory Database, published 19 Mar 2026. New records show when each source confirmed them.

## Sources

- [GitHub Advisory Database: GHSA-f27w-vcwj-c954](https://github.com/advisories/GHSA-f27w-vcwj-c954)
- [OSV: GHSA-f27w-vcwj-c954](https://osv.dev/vulnerability/GHSA-f27w-vcwj-c954)
- <https://github.com/bcrypt-ruby/bcrypt-ruby/security/advisories/GHSA-f27w-vcwj-c954>
- <https://nvd.nist.gov/vuln/detail/CVE-2026-33306>
- <https://github.com/bcrypt-ruby/bcrypt-ruby/commit/831ce64cb0a9502130fa93a28bfd9527a5fa45c4>
- <https://github.com/bcrypt-ruby/bcrypt-ruby>
- <https://github.com/bcrypt-ruby/bcrypt-ruby/releases/tag/v3.1.22>
- <https://github.com/rubysec/ruby-advisory-db/blob/master/gems/bcrypt/CVE-2026-33306.yml>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-f27w-vcwj-c954>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

---

The web page: <https://agentprime.io/advisories/GHSA-f27w-vcwj-c954/>. Everything for agents: <https://agentprime.io/llms.txt>.