Vulnerability in litestar (CVE-2026-25478)
Summary
Vulnerability in litestar (CVE-2026-25478). Confidential information can be exposed externally. Mitigation: upgrade to 2.20.0 or later.
Original description
The description as published by the source.
Summary
CORS origin validation can be bypassed because the allowed-origins allowlist is compiled into a regex without escaping metacharacters (notably .). An allowed origin like https://good.example can match https://goodXexample, resulting in Access-Control-Allow-Origin being set for an untrusted origin
Details
CORSConfig.allowed_origins_regex is constructed using a regex built from configured allowlist values and used with fullmatch() for validation. Because metacharacters are not escaped, a malicious origin can match unexpectedly. The check relies on allowed_origins_regex.fullmatch(origin).
PoC
Server (poc_cors_server.py)
from litestar import Litestar, get
from litestar.config.cors import CORSConfig
@get("/c")
async def c() -> str:
return "ok"
cors = CORSConfig(
allow_origins=["https://good.example"],
allow_credentials=True,
)
app = Litestar([c], cors_config=cors)
uvicorn poc_cors_server:app --host 127.0.0.1 --port 8002
Client (poc_cors_client.py)
import http.client
def req(origin: str) -> tuple[int, str | None]:
c = http.client.HTTPConnection("127.0.0.1", 8002, timeout=3)
c.request("GET", "/c", headers={"Origin": origin, "Host": "example.com"})
r = c.getresponse()
r.read()
acao = r.getheader("Access-Control-Allow-Origin")
c.close()
return r.status, acao
print("evil:", req("https://evil.example"))
print("bypass:", req("https://goodXexample"))
Expected (vulnerable behavior):
Origin: https://e…
Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory OSV
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-25478 has been found in litestar.
Confidential information can be exposed externally.
What to do: upgrade litestar to 2.20.0 or later.
If unsure, ask your IT team or search "litestar CVE-2026-25478" on the vendor's site.
CVE-2026-25478 (litestar) — CWE-942
Attack vector: remote (network-reachable) / unauthenticated
Patched: 2.20.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-942) exists in litestar.
Check the vendor advisory for the affected versions of litestar.
Severity: ?. Confidential information can be exposed externally.
Update to 2.20.0.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'litestar' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'litestar' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
litestarを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade litestar to 2.20.0ステージング環境で 2.20.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- advisory nvd.nist.gov
- package github.com
- web github.com
- web github.com
- web docs.litestar.dev
- web github.com