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

> Attackers can bypass host validation in Litestar by exploiting unescaped regex metacharacters in allowlist patterns, requiring specific configuration.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Feb 2026
- **Updated:** 10 Feb 2026
- **Also known as:** GHSA-93ph-p7v4-hwh4, PYSEC-2026-2196

## What is CVE-2026-25479?

CVE-2026-25479 is a medium-severity vulnerability in litestar-org litestar, published on 9 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official 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.

Weakness: CWE-185 (Incorrect Regular Expression)

## Which versions are affected by CVE-2026-25479?

3 open source packages ship an affected version, including litestar. It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `litestar` | PyPI | All versions | 2.20.0 |
| `litestar` | PyPI | From 2.19.0 | 2.20.0 |
| `litestar` | PyPI | From 2.19.0 | 2.20.0 |

Products: Litestar Litestar.

## How do I fix CVE-2026-25479?

Upgrade litestar to 2.20.0 or later.

## Is CVE-2026-25479 being exploited?

There is no known exploitation of CVE-2026-25479 in the wild and no public exploit code.

## Other vulnerabilities in litestar-org litestar

- [CVE-2024-52581](https://insights.sbomify.com/CVE-2024-52581/): Litestar allows unbounded resource consumption (DoS vulnerability) (high 8.2)
- [CVE-2026-25478](https://insights.sbomify.com/CVE-2026-25478/): Litestar has a CORS origin allowlist bypass due to unescaped regex metacharacters in allowed origins (high 7.4)
- [CVE-2026-25480](https://insights.sbomify.com/CVE-2026-25480/): FileStore key canonicalization collisions allow response cache mixup/poisoning (ASCII ord + Unicode NFKD) (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-25479 and fix it if it is affected.

What it is: CVE-2026-25479 is a medium-severity vulnerability in litestar-org litestar, published on 9 Feb 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-25479 in the wild and no public exploit code.

Affected packages and fixed versions:
- litestar (PyPI): affected all versions; fixed in 2.20.0
- litestar (PyPI): affected from 2.19.0; fixed in 2.20.0
- litestar (PyPI): affected from 2.19.0; fixed in 2.20.0

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-2026-25479/ (Markdown: https://insights.sbomify.com/CVE-2026-25479/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-25479
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-25479
- OSV: https://osv.dev/vulnerability/CVE-2026-25479

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-25479/
Summaries are generated and may contain mistakes; the official description above is the record.