Vulnerability in symfony/http-client (CVE-2026-48736)
Summary
Vulnerability in symfony/http-client (CVE-2026-48736). Confidential information can be exposed externally. Exploitable via NoPrivateNetworkHttpClient. Mitigation: upgrade to 5.4.53 or later.
Original description
The description as published by the source.
Symfony is a PHP framework for web and console applications and a set of reusable PHP components. From 5.4.0 to 5.4.53, 6.4.41, 7.4.13, and 8.0.13, NoPrivateNetworkHttpClient and IpUtils::PRIVATE_SUBNETS omitted IPv6 transition prefixes such as 6to4, NAT64, Teredo, and IPv4-compatible IPv6, allowing attacker-supplied URLs to represent private IPv4 targets in forms that IpUtils::isPrivateIp() did not block. This issue is fixed in versions 5.4.53, 6.4.41, 7.4.13, and 8.0.13.
Source: GitHub Security Advisories (Global) 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-2026-48736 has been found in symfony/http-client.
Attackers can target a specific entry point like NoPrivateNetworkHttpClient over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 8.6/10.
What to do: upgrade symfony/http-client to 5.4.53 or later.
If unsure, ask your IT team or search "symfony/http-client CVE-2026-48736" on the vendor's site.
CVE-2026-48736 (symfony/http-client) — CWE-184 / CVSS v3 8.6
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: NoPrivateNetworkHttpClient / false
Patched: 5.4.53 — 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-184) exists in symfony/http-client. Attackers reach the vulnerable code path via NoPrivateNetworkHttpClient without authentication.
Check the vendor advisory for the affected versions of symfony/http-client. Attack surface: NoPrivateNetworkHttpClient / false.
Severity: High (CVSS 8.6/10). Confidential information can be exposed externally.
Update to 5.4.53.
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 'symfony/http-client' . 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
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1Identify exposure identify
grep -r 'symfony/http-client' . | 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/http-client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 symfony/http-client to 5.4.53ステージング環境で 5.4.53 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
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-48736 symfony
- Ubuntu UBUNTU-CVE-2026-48736 symfony
References
- advisory github.com
- advisory github.com
- advisory nvd.nist.gov
- package github.com
- patch github.com
- patch github.com
- web github.com
- web github.com
- web github.com
- web symfony.com
- web github.com
- web github.com
- web github.com
- web github.com