# CVE-2026-123125: The Symfony Validator component IpValidator incompletely classifies internal addresses in the filtered modes of the Ip constraint, so some i


- **Severity:** Medium 6.3 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Fix available:** Yes
- **Published:** 5 Nov 2026
- **Updated:** 5 Nov 2026
- **Also known as:** DEBIAN-CVE-2026-123125, GHSA-4qpf-57w4-m3wc, UBUNTU-CVE-2026-123125

## What is CVE-2026-123125?

CVE-2026-123125 is a medium-severity vulnerability in sensiolabs symfony, published on 5 Nov 2026. 

### Official description

The Symfony Validator component IpValidator incompletely classifies internal addresses in the filtered modes of the Ip constraint, so some internal addresses are accepted as public, which can lead to Server-Side Request Forgery (SSRF) in Symfony versions 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.

In these modes, IpValidator relies on the PHP flags FILTER_FLAG_NO_PRIV_RANGE and FILTER_FLAG_NO_RES_RANGE to classify addresses as public, private, or reserved. These flags do not cover shared address space (100.64.0.0/10) or IPv4-mapped, IPv4-compatible, and 6to4 IPv6 addresses, which can embed internal IPv4 addresses. A value such as ::ffff:127.0.0.1 can therefore pass validation even though it points to an internal host.
Applications that rely on the Ip constraint to reject internal addresses, for example before making a server-side request to a user-supplied address, can be exposed to SSRF.

Weakness: CWE-918 (Server-Side Request Forgery), CWE-184 (Incomplete List of Disallowed Inputs)

## Which versions are affected by CVE-2026-123125?


## How do I fix CVE-2026-123125?

Upgrade to a fixed version.

## Is CVE-2026-123125 being exploited?

There is no known exploitation of CVE-2026-123125 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-123125 and fix it if it is affected.

What it is: CVE-2026-123125 is a medium-severity vulnerability in sensiolabs symfony, published on 5 Nov 2026. 
Exploitation: There is no known exploitation of CVE-2026-123125 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-2026-123125/ (Markdown: https://insights.sbomify.com/CVE-2026-123125/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-123125
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-123125
- OSV: https://osv.dev/vulnerability/CVE-2026-123125

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-123125/
Summaries are generated and may contain mistakes; the official description above is the record.