CVE-2020-5255Prevent cache poisoning via a Response Content-Type header
- 2.6LowCVSS base score
- 1.3%Exploitation in 30 daysEPSS · top 29% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By GitHub_M
- 3 months later
· 3 months later
Published
- 4 years later
· 4 years later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 3.1 | Low2.6 | CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L |
| NVDNVD · Modified | 3.1 | Medium4.3 | CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L |
- EPSS (exploitation in 30 days)
- 1.3% · top 29% of all CVEs (12 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Low 2.6.
Affected products
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- Packagistsymfony/http-foundationGHSA-mcx4-f5f5-4859 (opens in a new tab)
- Packagistsymfony/symfonyGHSA-mcx4-f5f5-4859 (opens in a new tab)
References
References4
- https://github.com/symfony/symfony/security/advisories/GHSA-mcx4-f5f5-4859 (opens in a new tab)x_refsource_CONFIRMx_transferred
- https://github.com/symfony/symfony/commit/dca343442e6a954f96a2609e7b4e9c21ed6d74e6 (opens in a new tab)x_refsource_MISCx_transferred
- https://symfony.com/blog/cve-2020-5255-prevent-cache-poisoning-via-a-response-content-type-header (opens in a new tab)x_refsource_MISCx_transferred
- FEDORA-2020-fade6a8df7 (opens in a new tab)vendor-advisoryx_refsource_FEDORAx_transferred
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2020-0351 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-mcx4-f5f5-4859 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2020-5255)Record last updated .