Vulnerability in anyio (CVE-2026-63374)
Summary
Vulnerability in anyio (CVE-2026-63374). Risk of unauthorized operations or information disclosure. Exploitable via idna. Mitigation: upgrade to 4.14.2 or later.
Original description
The description as published by the source.
Impact
Services using internationalized (non-ASCII) domain names are potentially vulnerable to TLS connections made from AnyIO's connect_tcp() or directly via TLSStream.wrap() where the connection has (through other means) been hijacked and redirected to a malicious server. The attacker would obtain a legitimate certificate using the IDNA 2003 encoded version of the domain name and offer it to the connecting client, making the certificate validate properly on the client's end.
Patches
The vulnerability will be patched in v4.14.2.
Workarounds
Encode host names via the idna package prior to connecting.
Source: NIST National Vulnerability Database NVD GitHub Advisory
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-2026-63374 has been found in anyio.
Attackers can target a specific entry point like idna over the network to misuse the product.
Risk of unauthorized operations or information disclosure.
What to do: upgrade anyio to 4.14.2 or later.
If unsure, ask your IT team or search "anyio CVE-2026-63374" on the vendor's site.
CVE-2026-63374 (anyio) — CWE-295
Attack surface: idna
Patched: 4.14.2 — apply immediately
Workaround: Encode host names via the idna package prior to connecting.
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-295) exists in anyio. Attackers reach the vulnerable code path via idna.
Check the vendor advisory for the affected versions of anyio. Attack surface: idna.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 4.14.2.
Workaround: Encode host names via the idna package prior to connecting.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'anyio' . 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 'anyio' . | 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
anyioを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply temporary workaround mitigate
Encode host names via the `idna` package prior to connecting.パッチが適用されるまでの応急処置として、Encode host names via the
idnapackage prior to connecting. を実施。回避策の副作用 (機能低下) を確認した上で。 -
3Apply patch patch
Upgrade anyio to 4.14.2ステージング環境で 4.14.2 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。
-
4Post-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
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-63374 python-anyio
- Ubuntu UBUNTU-CVE-2026-63374 python-anyio
References
- advisory github.com
- advisory nvd.nist.gov
- package github.com
- package pypi.org
- web github.com
- web github.com
- web github.com
- web github.com