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CVE-2026-46644
Vulnerability in symfony/polyfill (CVE-2026-46644)
Summary
vulnerability in symfony/polyfill (CVE-2026-46644). Risk of unauthorized operations or information disclosure. Exploitable via ``intl``. Mitigation: upgrade to `1.38.1` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-46644** has been found in symfony/polyfill.
Attackers can target a specific entry point like ``intl`` over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: ?/10.
What to do: upgrade symfony/polyfill to **1.38.1** or later.
If unsure, ask your IT team or search "symfony/polyfill CVE-2026-46644" on the vendor's site.
CVE-2026-46644 (symfony/polyfill) — CWE-1289 /
Attack surface: `intl` / `IDNA_ERROR_INVALID_ACE_LABEL` / `poc.kc1zs4.com` / `false`
Patched: `1.38.1` — 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.
❓ What is the problem
**A vulnerability** (CWE-1289) exists in symfony/polyfill. Attackers reach the vulnerable code path via ``intl`` without authentication.
📍 Affected scope
symfony/polyfill — . Attack surface: `intl` / `IDNA_ERROR_INVALID_ACE_LABEL` / `poc.kc1zs4.com` / `false`.
🔥 Severity
Severity: ?. Risk of unauthorized operations or information disclosure
🔧 How to fix
Update to **1.38.1**.
🛡️ Workaround
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
🔍 Detection
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run `grep -r 'symfony/polyfill' .` against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response Actions (7 steps)
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'symfony/polyfill' . | 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 `symfony/polyfill` を grep し、稼働しているサービス・バージョンを把握する。
-
6Apply patch patch
Upgrade symfony/polyfill to 1.38.1ステージング環境で 1.38.1 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と、Step 3 で見つけた異常検知の続報チェックを含めること。
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7Post-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 Step 3 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
composer
symfony/polyfill
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.38.1"}]}]
composer
symfony/polyfill-intl-idn
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.38.1"}]}]
Packagist
symfony/polyfill
[{"type":"ECOSYSTEM","events":[{"introduced":"1.17.1"},{"fixed":"1.38.1"}]}]
Packagist
symfony/polyfill-intl-idn
[{"type":"ECOSYSTEM","events":[{"introduced":"1.17.1"},{"fixed":"1.38.1"}]}]
References
- package https://github.com/symfony/polyfill
- web [email protected]
- web [email protected]
- web https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/polyfill-intl-idn/CVE-2026-46644.yaml
- web https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/polyfill/CVE-2026-46644.yaml
- web https://symfony.com/cve-2026-46644
- web https://github.com/advisories/GHSA-2xf4-cg6j-vhgq
- web [email protected]