RCE in Symfony
Description
The CachingHttpClient class from the HttpClient Symfony component relies on the HttpCache class to handle requests. HttpCache uses internal headers like X-Body-Eval and X-Body-File to control the restoration of cached responses. The class was initially written with surrogate caching and ESI support in mind (all HTTP calls come from a trusted backend in that scenario). But when used by CachingHttpClient and if an attacker can control the response for a request being made by the CachingHttpClient, remote code execution is possible.
Resolution
HTTP headers designed for internal use in HttpCache are now stripped from remote responses before being passed to HttpCache.
The patch for this issue is available here for the 4.4 branch.
Credits
I would like to thank Matthias Pigulla (webfactory GmbH) for reporting and fixing the issue.
Affected software
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| Platform | Package | Vulnerable versions | Fixed in |
|---|---|---|---|
| Composer package | symfony/http-kernel | >= 4.3.0, < 4.4.13, >= 5.0.0, < 5.1.5 | 4.4.13, 5.1.5 |
| Composer package | symfony/symfony | >= 4.3.0, < 4.4.13, >= 5.0.0, < 5.1.5 | 4.4.13, 5.1.5 |
References
- https://github.com/symfony/symfony/security/advisories/GHSA-754h-5r27-7x3r
- https://nvd.nist.gov/vuln/detail/CVE-2020-15094
- https://github.com/symfony/symfony/commit/d9910e0b33a2e0f993abff41c6fbc86951b66d78
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/http-kernel/CVE-2020-15094.yaml
- https://github.com/FriendsOfPHP/security-advisories/blob/master/symfony/symfony/CVE-2020-15094.yaml
- https://github.com/symfony/symfony
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/HNGUWOEETOFVH4PN3I3YO4QZHQ4AUKF3
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/VAQJXAKWPMWB7OL6QPG2ZSEQZYYPU5RC
- https://packagist.org/packages/symfony/http-kernel
- https://packagist.org/packages/symfony/symfony
- https://symfony.com/cve-2020-15094
- CVSS vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:H- Weakness (CWE)
CWE-212- Platform
- Composer
- Package
symfony/http-kernel, symfony/symfony- Disclosed
- 02.09.2020
- Updated
- 11.10.2026 10:22
Sources and licenses
OSV / GitHub Advisory Database - GHSA-754h-5r27-7x3r - CC BY 4.0
Vulnerability history: symfony/http-kernel
All published vulnerabilities of this package (Composer package), newest first. Shows whether this is a one-off slip or a package that needs watching.
- Total entries
- 8
- First → latest
- 09.2020 05.2026
- Without a fix
- 0
- Exploited in attacks
- 0
Severity breakdown
- High 4
- Medium 4
Disclosures per year
- 2020: 1
- 2021: 1
- 2022: 3
- 2023: 1
- 2024: 1
- 2025: 0
- 2026: 1
-
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