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Fencer Vulns
low 2.6

CVE-2020-5255 json

Prevent cache poisoning via a Response Content-Type header

published 2020-03-30 6 y ago modified 2026-09-10 1 mo ago also BIT-symfony-2020-5255 , EUVD-2020-0351 , GHSA-mcx4-f5f5-4859

cvss
2.6
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.3%
EPSS 1.3% chance of exploitation in 30 days, percentile 70%
public exploits
0
none known

Summary

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.

Patch / fix

  • packagist symfony/http-foundation 4.4.7, 5.0.7
  • packagist symfony/symfony 4.4.7, 5.0.7
  • bitnami symfony 4.4.7, 5.0.7
  • sensiolabs symfony 4.4.7, 5.0.7
  • symfony Debian 14, Debian 13, Debian 12 4.4.8-1

debian advisories DEBIAN-CVE-2020-5255

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-5255 updated cvss 2.6

php-symfony: Response without Content-Type header could result in cache poisoning

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.30% chance of exploitation in the next 30 days, higher than 70% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 2.6 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L
GitHub 3.1 2.6 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L
NVD 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
NVD 2.0 4.0 AV:N/AC:L/Au:S/C:N/I:N/A:P
OSV 3.1 4.3 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

Affected packages

ecosystem package affected fixed in
packagist symfony/http-foundation
>=4.4.0, <4.4.7
>=5.0.0, <5.0.7
4.4.7
5.0.7
packagist symfony/symfony
>=4.4.0, <4.4.7
>=5.0.0, <5.0.7
4.4.7
5.0.7
bitnami symfony
>=4.4.0, <4.4.7
>=5.0.0, <5.0.7
4.4.7
5.0.7

Affected products

  • symfony symfony

Classification

Weakness
  • CWE-435 Improper Interaction Between Multiple Correctly-Behaving Entities
  • CWE-20 Improper Input Validation

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.