---
title: "Security digest: May 21, 2026"
url: https://erroneo.us/security/2026-05-21/
description: "May 21, 2026 vulnerability digest: 1 brief (BadHost); 2 CISA KEV additions (Langflow, Trend Micro); 7 critical advisories (npm, PyPI, Go, crates.io…). What…"
type: security-digest-day
section: "Security Digest"
date_published: 2026-05-21
date_modified: 2026-09-02
publisher: erroneo.us
author: erroneo.us Security Desk
license: All rights reserved. Quote with attribution and a link.
---

# Security digest: May 21, 2026

1 editorial brief, 2 known exploited (cisa kev) additions and 7 critical advisories.

## Take stock

- Patch this week: BadHost . Teams running Starlette or FastAPI apps, or Python AI infrastructure built on them (LiteLLM, vLLM, MCP servers), whose middleware checks request.url or request.url.path, especially with uvicorn, hypercorn, granian or daphne exposed without a reverse proxy.
- Do you run any of these? Trend Micro Apex One, Langflow Langflow. They are being exploited in the wild (CISA KEV). Patch or mitigate if you do; CISA’s federal deadline is 2026-06-04.
- npm: 3 critical advisories ( @hulumi/policies , @boxlite-ai/boxlite ). Check with npm audit (or: npm ls <package>) .
- PyPI: 3 critical advisories ( pyfory , boxlite ). Check with pip-audit (or: pip show <package>) .
- Go: 3 critical advisories ( github.com/boxlite-ai/boxlite/sdks/go , github.com/fission/fission ). Check with govulncheck ./... .
- crates.io (Rust): 2 critical advisories ( boxlite , boxlite-cli ). Check with cargo audit .
- Composer (PHP): 2 critical advisories ( twig/twig , concrete5/concrete5 ). Check with composer audit .
- None of it touches your stack? Then there is nothing to do today. That is a result, not a failure to read carefully.

## Editorial briefs

- **Patch this week** [Starlette BadHost: Host Header Auth Bypass in CISA KEV](https://erroneo.us/security/briefs/starlette-badhost-host-header-bypass-cve-2026-48710/index.md): Bump starlette to 1.0.1 or later in every Python service this week; it is urgent where an ASGI server faces untrusted clients directly and middleware makes security decisions from request.url.

## Known exploited (CISA KEV)

- [CVE-2026-34926](https://erroneo.us/security/cve/CVE-2026-34926/index.md) Trend Micro Apex One: Trend Micro Apex One (On-Premise) Directory Traversal Vulnerability (CISA due 2026-06-04)
- [CVE-2025-34291](https://erroneo.us/security/cve/CVE-2025-34291/index.md) Langflow Langflow: Langflow Origin Validation Error Vulnerability (CISA due 2026-06-04)

## Critical advisories

- [GHSA-q2f7-m237-v562](https://erroneo.us/security/ghsa/GHSA-q2f7-m237-v562/index.md) @hulumi/policies: GitHub OIDC trust policy bypass via AWS set-qualified condition operators — npm @hulumi/policies < 1.3.2 → 1.3.2
- [CVE-2026-48207](https://erroneo.us/security/cve/CVE-2026-48207/index.md) Apache Fory PyFory Deserialization of Untrusted Data — PyPI pyfory >= 0.13.0, < 1.0.0 → 1.0.0
- [CVE-2026-46695](https://erroneo.us/security/cve/CVE-2026-46695/index.md) BoxLite: Permission Bypass Allows Modification of Read-Only Files — PyPI boxlite < 0.9.0 → 0.9.0; npm @boxlite-ai/boxlite < 0.9.0 → 0.9.0; Go github.com/boxlite-ai/boxlite/sdks/go < 0.9.0 → 0.9.0
- [CVE-2026-46703](https://erroneo.us/security/cve/CVE-2026-46703/index.md) Boxlite: Path Traversal Vulnerability Leads to Arbitrary File Write on the Host — PyPI boxlite < 0.9.0 → 0.9.0; crates.io (Rust) boxlite-cli < 0.9.0 → 0.9.0; crates.io (Rust) boxlite < 0.9.0 → 0.9.0
- [CVE-2026-46633](https://erroneo.us/security/cve/CVE-2026-46633/index.md) Twig: PHP code injection via `{% use %}` template name — Composer (PHP) twig/twig < 3.26.0 → 3.26.0
- [CVE-2026-8134](https://erroneo.us/security/cve/CVE-2026-8134/index.md) Concrete CMS Vulnerable to Relative Path Traversal — Composer (PHP) concrete5/concrete5 < 9.5.1 → 9.5.1
- [CVE-2026-46614](https://erroneo.us/security/cve/CVE-2026-46614/index.md) Fission router exposes /fission-function/<ns>/<name> on its public listener, allowing invocation of any function without an HTTPTrigger — Go github.com/fission/fission <= 1.22.0 → 1.23.0

---
Source page: https://erroneo.us/security/2026-05-21/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt