Vulnerability in anyio (CVE-2026-64847)
Summary
Vulnerability in anyio (CVE-2026-64847). Risk of unauthorized operations or information disclosure. Exploitable via stderr. Mitigation: upgrade to 4.14.2 or later.
Original description
The description as published by the source.
Impact
AnyIO starts process-pool workers with stderr connected to a pipe but never drains that pipe. The worker redirects stdin and stdout to /dev/null to protect its protocol, but does not redirect stderr even though the documentation says all three standard streams are redirected. Worker code that writes enough attacker-influenced data to stderr can fill the pipe, block before returning the stdout protocol response, and wedge the awaiting process-pool call.
Anyone who runs untrusted or faulty code that writes too much to stderr is at risk.
Patches
This vulnerability will be patched in v4.14.2.
Workarounds
Closing sys.stderr in the target function should at least prevent the deadlock.
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-2026-64847 has been found in anyio.
Attackers can target a specific entry point like stderr 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-2026-64847" on the vendor's site.
CVE-2026-64847 (anyio) — CWE-770
Attack surface: stderr / sys.stderr
Patched: 4.14.2 — apply immediately
Workaround: Closing sys.stderr in the target function should at least prevent the deadlock.
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-770) exists in anyio. Attackers reach the vulnerable code path via stderr.
Check the vendor advisory for the affected versions of anyio. Attack surface: stderr / sys.stderr.
Severity: ?. Risk of unauthorized operations or information disclosure.
Update to 4.14.2.
Workaround: Closing sys.stderr in the target function should at least prevent the deadlock.
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
Closing `sys.stderr` in the target function should at least prevent the deadlock.パッチが適用されるまでの応急処置として、Closing
sys.stderrin the target function should at least prevent the deadlock. 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
References
- web github.com
- web github.com
- web github.com
- web github.com
- web github.com