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CVE-2026-48784 medium CVSS 6.1

Vulnerability in symfony/routing (CVE-2026-48784)

Summary

Vulnerability in symfony/routing (CVE-2026-48784). Risk of unauthorized operations or information disclosure. Exploitable via strtr. Mitigation: upgrade to 8.0.13 or later.

Original description

The description as published by the source.

Description

Symfony\Component\Routing\Generator\UrlGenerator::doGenerate() percent-encodes . and .. path segments so that the generated URL still resolves to the originating route after RFC 3986 §5.2.4 dot-segment removal (which strict RFC-3986 consumers — routers, reverse proxies, HTTP clients — perform before percent-decoding).

The encoding was implemented as strtr($url, ['/../' => '/%2E%2E/', '/./' => '/%2E/']) plus a trailing-segment fixup. strtr advances past the trailing / of each match, so the next dot-segment in a chained sequence was left unescaped:

Input Output (before fix) Expected
/../../../ /%2E%2E/../%2E%2E/ /%2E%2E/%2E%2E/%2E%2E/
/foo/../../../bar /foo/%2E%2E/../%2E%2E/bar /foo/%2E%2E/%2E%2E/%2E%2E/bar

When a route exposes a parameter constrained by a permissive requirement (.+, .*, or similar) that accepts dots and slashes, attacker-controlled chained .. or . segments produce a generated URL that, under strict RFC 3986 normalization, collapses to a different path than the originating route. The Twig path() / url() helpers and any server-side use of UrlGenerator are affected. Same class of route round-trip integrity issue as CVE-2026-45065.

Note: WHATWG-conformant bro…

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-2026-48784 has been found in symfony/routing.
Attackers can target a specific entry point like strtr over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 6.1/10.
What to do: upgrade symfony/routing to 8.0.13 or later.
If unsure, ask your IT team or search "symfony/routing CVE-2026-48784" on the vendor's site.

CVE-2026-48784 (symfony/routing) — CWE-172 / CVSS v3 6.1
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: strtr / UrlGenerator / preg_replace_callback
Patched: 8.0.13 — 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-172) exists in symfony/routing. Attackers reach the vulnerable code path via strtr without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of symfony/routing. Attack surface: strtr / UrlGenerator / preg_replace_callback.

🔥 Severity

Severity: Medium (CVSS 6.1/10). Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 8.0.13.

🛡️ 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/routing' . 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

  1. 1
    Identify exposure identify 
    grep -r 'symfony/routing' . | 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/routing を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade symfony/routing to 8.0.13

    ステージング環境で 8.0.13 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。

  3. 3
    Post-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

composer symfony/routing
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.0.13"}]}]
composer symfony/symfony
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"8.0.13"}]}]
Packagist symfony/routing
[{"type":"ECOSYSTEM","events":[{"introduced":"8.0.0"},{"fixed":"8.0.13"}]}]
Packagist symfony/symfony
[{"type":"ECOSYSTEM","events":[{"introduced":"8.0.0"},{"fixed":"8.0.13"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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