How severe is CVE-2026-45074?

No CVSS score has been assigned to CVE-2026-45074 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-45074?

CVE-2026-45074 affects the following packages: symfony/security-http (Packagist), symfony/security-http (Packagist), symfony/symfony (Packagist), symfony/symfony (Packagist). Ecosystems affected: Packagist.

How do I fix CVE-2026-45074?

Update symfony/security-http to 7.4.12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45074 is resolved across your whole dependency graph.

How do I detect CVE-2026-45074 in my Packagist dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/security-http, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-45074 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2026-45074 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-45074 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-45074?

CVE-2026-45074 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 40th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-45074?

CVE-2026-45074 is classified as CWE-290 (CWE-290). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-45074 published, and has it been updated?

CVE-2026-45074 was published on July 14, 2026 and was last updated on August 12, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐘 Packagist

Not in CISA KEV

CVE-2026-45074 — security-http

Fix: symfony/symfony@5ba145d

CVE-2026-45074 is a CWE-290 vulnerability in symfony/security-http. A fix is available for symfony/security-http — see the affected versions and patch details below.

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

Also known asGHSA-j8gj-9rm5-4xhx

Published

Jul 14, 2026

Updated

Aug 12, 2026

Affected

4 pkgs

Patched

4 / 4

Exploits

None indexed

Exploitation data as of Oct 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

A successful exploit gives an attacker total control of the affected component, not partial access.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-45074.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs40th percentile — riskier than 40% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

4 pkgs affected

🐘symfony/security-http🐘symfony/security-http🐘symfony/symfony🐘symfony/symfony

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Packagist packages — download data is not available via public APIs for these ecosystems.

Description

Cas2Handler builds this service parameter from Request::getSchemeAndHttpHost(), which reflects the attacker-controlled HTTP Host header whenever Symfony's framework.trusted_hosts setting is not configured (the default). An attacker who controls any other application registered with the same CAS server can replay a victim's ticket against the Symfony application, with a spoofed Host header, and be authenticated as that victim.

Resolution

A new required service_url configuration option is introduced on Cas2Handler. The CAS service parameter sent to the validation endpoint is now built from this configured URL instead of being derived from the request's Host header, preventing cross-service ticket replay via Host header spoofing.

The patch for this issue is available here for branch 7.4.

Credits

Symfony would like to thank Claude Mythos Preview (via Project Glasswing) for reporting the issue and Nicolas Grekas for providing the fix.

Affected Packages

4 total 4 fixed

Ecosystem	Package	Vulnerable range	Fix
🐘Packagist	`symfony/security-http`	≥ 7.1.0&&< 7.4.12	7.4.12`composer require symfony/security-http:^7.4.12`
🐘Packagist	`symfony/security-http`	≥ 8.0.0&&< 8.0.12	8.0.12`composer require symfony/security-http:^8.0.12`
🐘Packagist	`symfony/symfony`	≥ 7.1.0&&< 7.4.12	7.4.12`composer require symfony/symfony:^7.4.12`
🐘Packagist	`symfony/symfony`	≥ 8.0.0&&< 8.0.12	8.0.12`composer require symfony/symfony:^8.0.12`

Affected Products

1 product · 2 configurations

Application

symfonysensiolabs

≥ 8.0.0 && < 8.0.12

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/security-http, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update symfony/security-http to 7.4.12 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-45074 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

`Cas2Handler` builds this `service` parameter from `Request::getSchemeAndHttpHost()`, which reflects the attacker-controlled HTTP `Host` header whenever Symfony's `framework.trusted_hosts` setting is not configured (the default). An attacker who controls any *other* application registered with the same CAS server can replay a victim's ticket against the Symfony application, with a spoofed `Host` header, and be authenticated as that victim. ### Resolution A new required `service_url` configuration option is introduced on `Cas2Handler`. The CAS `service` parameter sent to the validation endpoi

O3 Security · Impact-Aware SCA

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