GHSA-q8hg-pf8v-cxrv — symfony/http-kernel
HIGHGHSA-q8hg-pf8v-cxrv is a high-severity (CVSS 8.1) CWE-203 vulnerability in symfony/http-kernel. A fix is available for symfony/http-kernel — see the affected versions and patch details below.
Symfony Http-Kernel has non-constant time comparison in UriSigner
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-q8hg-pf8v-cxrv plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 377,166 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
symfony/http-kernel🐘symfony/http-kernel🐘symfony/http-kernel🐘symfony/http-kernel🐘symfony/symfony🐘symfony/symfony🐘symfony/symfony🐘symfony/symfonyReal-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
When checking the signature of an URI (an ESI fragment URL for instance), the URISigner did not used a constant time string comparison function, resulting in a potential remote timing attack vulnerability.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐘Packagist | symfony/http-kernel | ≥ 2.2.0&&< 2.8.52 | 2.8.52composer require symfony/http-kernel:^2.8.52 |
| 🐘Packagist | symfony/http-kernel | ≥ 3.0.0&&< 3.4.35 | 3.4.35composer require symfony/http-kernel:^3.4.35 |
| 🐘Packagist | symfony/http-kernel | ≥ 4.0.0&&< 4.2.12 | 4.2.12composer require symfony/http-kernel:^4.2.12 |
| 🐘Packagist | symfony/http-kernel | ≥ 4.3.0&&< 4.3.8 | 4.3.8composer require symfony/http-kernel:^4.3.8 |
| 🐘Packagist | symfony/symfony | ≥ 2.2.0&&< 2.8.52 | 2.8.52composer require symfony/symfony:^2.8.52 |
| 🐘Packagist | symfony/symfony | ≥ 3.0.0&&< 3.4.35 | 3.4.35composer require symfony/symfony:^3.4.35 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for symfony/http-kernel, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update symfony/http-kernel to 2.8.52 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-q8hg-pf8v-cxrv 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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-q8hg-pf8v-cxrv can be triaged on real exposure rather than presence alone.
Tailored to GHSA-q8hg-pf8v-cxrv. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-q8hg-pf8v-cxrv in your dependencies?
O3 Security finds GHSA-q8hg-pf8v-cxrv across Packagist dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.