CVE-2020-5255
mediumpriority · track · 17EPSS 0.013 · 70 %ileEUUSEPSS · scored 2026-10-27
In Symfony before versions 4.4.7 and 5.0.7, when a `Response` does not contain a `Content-Type` header, affected versions of Symfony can fallback to the format defined in the `Accept` header of the request, leading to a possible mismatch between the response's content and `Content-Type` header. When the response is cached, this can prevent the use of the website by other users. This has been patched in versions 4.4.7 and 5.0.7.
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–medium · 2.6–4.3
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (10)
Products and version ranges known to be affected.
advisories (2)
Vendor and ecosystem advisories describing this.
- GHSA-mcx4-f5f5-4859Prevent cache poisoning via a Response Content-Type header in Symfony2020-03-30ghsa · osvUS
Description ----------- When a `Response` does not contain a `Content-Type` header, Symfony falls back to the format defined in the `Accept` header of the request, leading to a possible mismatch between the response's content and `Content-Type` header. When the response is cached, this can lead to a corrupted cache where the cached format is not the right one. Resolution ---------- Symfony does not use the `Accept` header anymore to guess the `Content-Type`. The patch for this issue is available [here](https://github.com/symfony/symfony/commit/dca343442e6a954f96a2609e7b4e9c21ed6d74e6) for the 4.4 branch. Credits ------- I would like to thank Xavier Lacot from JoliCode for reporting & Yonel Ceruto and Tobias Schultze for fixing the issue.
- BIT-symfony-2020-52552024-03-06vendor · osvUS
In Symfony before versions 4.4.7 and 5.0.7, when a `Response` does not contain a `Content-Type` header, affected versions of Symfony can fallback to the format defined in the `Accept` header of the request, leading to a possible mismatch between the response's content and `Content-Type` header. When the response is cached, this can prevent the use of the website by other users. This has been patched in versions 4.4.7 and 5.0.7.
also known as (5)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (14)
External citations — patches, advisories, analysis.
- https://github.com/symfony/symfony/commit/dca343442e6a954f96a2609e7b4e9c21ed6d74e6cnnvd
- https://github.com/symfony/symfony/security/advisories/GHSA-mcx4-f5f5-4859cnnvd
- https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/C36JLPHUPKDFAX6D5WYFC4ALO2K7RDUQ/cnnvd
- https://nvd.nist.gov/vuln/detail/CVE-2020-5255cnnvd
- https://symfony.com/blog/cve-2020-5255-prevent-cache-poisoning-via-a-response-content-type-headercnnvd
- https://vigilance.fr/vulnerability/Symfony-spoofing-via-Content-Type-Cache-Poisoning-31908cnnvd
- https://github.com/symfony/symfony/commit/dca343442e6a954f96a2609e7b4e9c21ed6d74e6enisa_euvd
- https://github.com/symfony/symfony/security/advisories/GHSA-mcx4-f5f5-4859enisa_euvd
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