Symfony HttpClient: Scoped Client Can Send Credentials to Other Hosts

Published as "ScopingHttpClient Sends the Credentials of Its Default Scope to Other Origins Through Network-Path References"

high Symfony Symfony components · Last reviewed Nov 10, 2026

CVE: CVE-2026-121971
GHSA: None
Packagist: PKSA-yd1s-kk7g-k2j3
Reported: Nov 4, 2026

Can send a scoped client's token or other credentials to another host when an attacker controls the start of a URL the app requests.

Affected and fixed versions

In 2 packages: symfony/http-client and symfony/symfony. Find the row for the version you run, and update to the release next to it.

If you run	Update to	Support
8.1.0 – 8.1.10	8.1.11	Supported
7.4.0 – 7.4.22	7.4.23	Supported
6.4.0 – 6.4.49	6.4.50	Supported
5.4.0 – 5.4.55	5.4.56	Supported

Show 15 older branches, no longer supported

8.0.0 – 8.0.x	8.1.11
7.0.0 – 7.0.x	7.4.23
7.1.0 – 7.1.x	7.4.23
7.2.0 – 7.2.x	7.4.23
7.3.0 – 7.3.x	7.4.23
6.0.0 – 6.0.x	6.4.50
6.1.0 – 6.1.x	6.4.50
6.2.0 – 6.2.x	6.4.50
6.3.0 – 6.3.x	6.4.50
4.3.0 – 4.3.x	5.4.56
4.4.0 – 4.x	5.4.56
5.0.0 – 5.0.x	5.4.56
5.1.0 – 5.1.x	5.4.56
5.2.0 – 5.2.x	5.4.56
5.3.0 – 5.3.x	5.4.56

Upgrade

Run the line for the branch you are on. 1 other package listed above is affected too; update it the same way.

composer require symfony/http-client:^8.1.11
composer require symfony/http-client:^7.4.23
composer require symfony/http-client:^6.4.50
composer require symfony/http-client:^5.4.56

What this means

Symfony's ScopingHttpClient could send your API credentials, such as a bearer token, to a different host than the one they were set up for. An attacker who controls the start of a URL your app requests could receive them.

Who is affected

Apps on symfony/http-client (also part of symfony/symfony) that use a client built with HttpClient::createForBaseUri(), ScopingHttpClient::forBaseUri(), or a scoped client with a base_uri under framework.http_client.scoped_clients. The app also has to pass that client a URL an attacker can influence, such as a path from user input or a URL from a remote API response.

The Symfony advisory says some relative URLs that point to another host kept the default scope's options, including auth_bearer, auth_basic, headers and local_cert. Apps that only pass fixed paths to these clients aren't exposed.

What to do

Update to 5.4.56, 6.4.50, 7.4.23 or 8.1.11. If you're on 8.0, update to 8.1.11. The fix drops the default scope's options when a URL resolves to a different scheme, host, port or user info.

Reported by Thomas Chauchefoin of Trail of Bits.

Check your app with an agent

Paste this into a coding agent that can read your project, such as Claude Code, Codex or Amp. It checks your composer.lock against the versions above and tells you what to update, without changing anything.

Check whether the PHP project you have access to is affected by this security advisory, and tell me what to update. Do a read-only check: don't edit files, don't run composer update or composer require, and don't try to reproduce the flaw.

Advisory: Symfony HttpClient: Scoped Client Can Send Credentials to Other Hosts (CVE-2026-121971)
Details: https://phpnews.net/security/symfony/pksa-yk9m-qbjr-81kg

Affected versions, as Composer constraints:
- symfony/http-client, symfony/symfony: >=4.3.0,<4.4.0|>=4.4.0,<5.0.0|>=5.0.0,<5.1.0|>=5.1.0,<5.2.0|>=5.2.0,<5.3.0|>=5.3.0,<5.4.0|>=5.4.0,<5.4.56|>=6.0.0,<6.1.0|>=6.1.0,<6.2.0|>=6.2.0,<6.3.0|>=6.3.0,<6.4.0|>=6.4.0,<6.4.50|>=7.0.0,<7.1.0|>=7.1.0,<7.2.0|>=7.2.0,<7.3.0|>=7.3.0,<7.4.0|>=7.4.0,<7.4.23|>=8.0.0,<8.1.0|>=8.1.0,<8.1.11

Fixed releases on branches that still get security fixes:
- 8.1.0 – 8.1.10: update to 8.1.11
- 7.4.0 – 7.4.22: update to 7.4.23
- 6.4.0 – 6.4.49: update to 6.4.50
- 5.4.0 – 5.4.55: update to 5.4.56

1. Find every composer.lock in the project outside vendor/ (a monorepo can have one per app) and read the installed version of each package above. Packages installed as dependencies of other packages count too.
2. Compare each installed version with its constraint: "|" separates alternative ranges, and "," means both bounds apply.
3. For each affected install, read "What this means" at https://phpnews.net/security/symfony/pksa-yk9m-qbjr-81kg and check whether the project meets the conditions it describes (a feature in use, a config value, a driver). Say which conditions you could check and which you couldn't.
4. Report a table: lock file | package | installed version | affected (yes, no or unknown) | conditions met (yes, no or unknown) | update to | evidence. For each affected package, give the command that would fix it, without running it: composer update <package> --with-dependencies when it is only installed as a dependency of another package, or composer require with the fixed version when composer.json requires it directly. If the installed version is on a branch with no fixed release listed, say it needs a move to a newer branch.

Sources

← All Symfony advisories