CVE-2026-123125 The Symfony Validator component IpValidator incompletely classifies internal addresses in the filtered modes of the Ip constraint, so some i
- Exploited in the wild
- Not known
- Fix
- Available
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.
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.
Sources
Also known as DEBIAN-CVE-2026-123125, GHSA-4qpf-57w4-m3wc, UBUNTU-CVE-2026-123125.