# CVE-2026-121971: Symfony: ScopingHttpClient Sends the Credentials of Its Default Scope to Other Origins Through Network-Path References


- **Severity:** High 8.2 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 4 Nov 2026
- **Updated:** 5 Nov 2026
- **Also known as:** DEBIAN-CVE-2026-121971, GHSA-gq53-v8w2-gjhj, GHSA-wgw5-9p87-vhvp, UBUNTU-CVE-2026-121971

## What is CVE-2026-121971?

CVE-2026-121971 is a high-severity vulnerability in sensiolabs symfony, published on 4 Nov 2026. 

### Official description

The component ScopingHttpClient in Symfony HttpClient merges the options of its default scope (such as auth_bearer or auth_basic) into a request before resolving a relative URL against the base_uri, allowing a network-path reference such as "//evil.example/steal" to be sent to another origin together with the default scope’s credentials, and resulting in potential disclosure of those credentials to an attacker-controlled server. This affects Symfony in versions 5.x prior to 5.4.56, 6.x prior to 6.4.50, 7.x prior to 7.4.23, and 8.x prior to 8.1.11.

The resolved URL falls outside the origin of the base URI, yet it keeps the merged options, whereas the absolute spelling "https://evil.example/steal" receives none. The same happens with a different port or user-info part on the same host.

This is reachable whenever an attacker controls the beginning of a URL passed to a client built with a base_uri and credentials, including those created with HttpClient::createForBaseUri() or configured under framework.http_client.scoped_clients.

To solve the issue, after resolving a relative URL against the base URI of the default scope, ScopingHttpClient now compares the scheme and authority of the result with those of the base URI, parsed the way the request is sent.

Weakness: CWE-522 (Insufficiently Protected Credentials), CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor)

## Which versions are affected by CVE-2026-121971?


## How do I fix CVE-2026-121971?

Upgrade to a fixed version.

## Is CVE-2026-121971 being exploited?

There is no known exploitation of CVE-2026-121971 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-121971 and fix it if it is affected.

What it is: CVE-2026-121971 is a high-severity vulnerability in sensiolabs symfony, published on 4 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-121971 in the wild and no public exploit code.

Affected product: sensiolabs symfony. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-121971/ (Markdown: https://insights.sbomify.com/CVE-2026-121971/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-121971
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-121971
- OSV: https://osv.dev/vulnerability/CVE-2026-121971

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-121971/
Summaries are generated and may contain mistakes; the official description above is the record.