# Symfony: UrlGenerator Dot-Segment Encoding Skips Every Other Chained \`../\` or \`./\` → Generated URL Collapses Off-Route Under RFC 3986 Normalization

Advisory record · `GHSA-h5x3-xfc9-m39h`

- **Identifiers:** `GHSA-h5x3-xfc9-m39h` · `CVE-2026-48784` · `PKSA-bf7t-jnpz-492k` · `PKSA-nshj-ydrr-y3c1`
- **State:** Confirmed
- **Severity:** CVSS 5.1 Medium
- **Critical:** No
- **Weakness (CWE):** [CWE-172](https://cwe.mitre.org/data/definitions/172.html) · [CWE-601](https://cwe.mitre.org/data/definitions/601.html)
- **Tags:** [Open redirect](https://agentprime.io/advisories/tag/open-redirect.md) · [CWE-172](https://agentprime.io/advisories/tag/cwe-172.md)
- **Published:** 15 Jun 2026
- **Updated:** 10 Sept 2026
- **Reviewed by a person:** No

Published by the GitHub Advisory Database at 15 Jun 2026, 17:33 UTC. agentprime has not analysed this yet, so whether it affects any app is not known.

## Affected packages

- `symfony/routing` (Packagist): affected `<5.4.53 || >=6.0.0, <6.4.41 || >=7.0.0, <7.4.13 || >=8.0.0, <8.0.13`; fixed in `5.4.53`, `6.4.41`, `7.4.13`, `8.0.13`
- `symfony/symfony` (Packagist): affected `<5.4.53 || >=6.0.0, <6.4.41 || >=7.0.0, <7.4.13 || >=8.0.0, <8.0.13`; fixed in `5.4.53`, `6.4.41`, `7.4.13`, `8.0.13`

## Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

## Severity and exploitation

- 5.1 Medium, CVSS 4.0: `CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N`, from CNA (GitHub_M)

- **CISA KEV:** Not listed.
- **EPSS:** 0.0035, the 28th percentile, on 6 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

## Timeline

- 31 Oct 2026, 14:00 UTC: First seen by agentprime
- 31 Oct 2026, 14:00 UTC: [Confirmed by OSV](https://osv.dev/vulnerability/GHSA-h5x3-xfc9-m39h)

## Sources

- [GitHub Advisory Database: GHSA-h5x3-xfc9-m39h](https://github.com/advisories/GHSA-h5x3-xfc9-m39h)
- [OSV: GHSA-h5x3-xfc9-m39h](https://osv.dev/vulnerability/GHSA-h5x3-xfc9-m39h)
- <https://github.com/symfony/symfony/security/advisories/GHSA-h5x3-xfc9-m39h>
- <https://github.com/symfony/symfony/commit/4b63c3a3f7af04ecd79c89a594b0b02a01990b1d>
- <https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/routing/CVE-2026-48784.yaml>
- <https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2026-48784.yaml>
- <https://github.com/symfony/symfony>
- <https://symfony.com/cve-2026-48784>

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.

## Check whether this affects you

A Match means an installed version is in the affected range above. Most don’t affect the app; agentprime hasn’t analysed this one yet.

- With the agentprime MCP server (<https://api.agentprime.io/mcp>), ask your agent to check the project: `check_lockfile` sends a lockfile, `check_packages` a list of installed packages, and both return the Matches and the upgrades that clear them. `get_advisory` returns this record. Setup: <https://agentprime.io/mcp.md>
- In a browser: <https://agentprime.io/check/> reads your lockfile in the browser, never uploading it.
- Whether it touches your code, with file and line: the Claude Code plugin, <https://agentprime.io/plugin.md>
- As JSON: <https://api.agentprime.io/v1/advisories/GHSA-h5x3-xfc9-m39h>, or `POST https://api.agentprime.io/v1/match` with your packages (<https://agentprime.io/api.md>)

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The web page: <https://agentprime.io/advisories/GHSA-h5x3-xfc9-m39h/>. Everything for agents: <https://agentprime.io/llms.txt>.