Symfony HttpClient: DNS Rebinding Lets NoPrivateNetworkHttpClient Probe Ports

Published as "NoPrivateNetworkHttpClient Does Not Pin the Checked IP of Cached Hosts, Letting DNS Rebinding Enumerate Internal Ports: Incomplete Fix for CVE-2024-50342"

low Symfony Symfony components · Last reviewed Nov 10, 2026

CVE: CVE-2026-123119
GHSA: None
Packagist: PKSA-gfw6-4rnd-4533
Reported: Nov 4, 2026

Lets an attacker who controls a host's DNS probe internal hosts and ports through repeated NoPrivateNetworkHttpClient requests to that host.

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 NoPrivateNetworkHttpClient is meant to stop your app from making requests to private networks. A gap in it lets an attacker who controls a domain's DNS find out which internal hosts and ports are open.

The client checked a host's IP address the first time it looked the host up. On later requests to the same host, it let the lookup happen again without pinning the checked address. DNS rebinding (a DNS server answering with a public IP first and a private one later) takes advantage of that. The request is still stopped before anything is sent, but the connection is made, and the error differs depending on whether the port is open. This is an incomplete fix for CVE-2024-50342. See the Symfony advisory and the fix.

Who is affected

Apps that use NoPrivateNetworkHttpClient to fetch URLs that users supply, and send several requests to the same host through the same client. Symfony's example is an app that fetches several URLs from a repository a user provides.

Apps that don't use NoPrivateNetworkHttpClient aren't affected. The attacker learns which internal ports are open, not what is behind them, which is why the CVSS score is 2.3 (low).

What to do

Update symfony/http-client (or symfony/symfony) to 5.4.56, 6.4.50, 7.4.23 or 8.1.11, depending on your branch.

Reported by Eirik Stanghelle Morland of Packagist.

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: DNS Rebinding Lets NoPrivateNetworkHttpClient Probe Ports (CVE-2026-123119)
Details: https://phpnews.net/security/symfony/pksa-gd5w-xsj1-63jv

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-gd5w-xsj1-63jv 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

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