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CVE-2020-5255

14
FAUCET Score

CVE-2020-5255 affects Symfony versions prior to 4.4.7 and 5.0.7. The vulnerability arises when a Response lacks a Content-Type header, causing Symfony to default to the Accept header's format, potentially creating a mismatch between content and header. This can lead to caching issues that disrupt website access for other users. Rated as Medium severity (CVSS 4.3), the vulnerability has a low attack complexity and requires low privileges, with a potential impact of denial of service (availability). There is no confidentiality or integrity impact. Currently, there is no evidence of active exploitation, nor is exploit code publicly available in Metasploit, Nuclei, or ExploitDB. Community discussion and media coverage for this CVE are minimal.

Impacted Technologies

VendorProductVersion(s)CPE
>= 4.4.0, < 4.4.7CPE matchmatch criteria
cpe:2.3:a:sensiolabs:symfony:*:*:*:*:*:*:*:*
>= 5.0.0, < 5.0.7CPE matchmatch criteria
cpe:2.3:a:sensiolabs:symfony:*:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

2.6LOW

CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:N/I:N/A:L

Attack Vector
NETWORK
Attack Complexity
HIGH
Privileges Required
LOW
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
LOW
Exploitability Score
1.2
Impact Score
1.4
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.30%
Probability of exploitation in next 30 days
EPSS Percentile
67.4%
Percentile rank of EPSS score among Peer Group
As of 2026-07-25
Model: v2026.06.15
This CVE's current EPSS score of 0.0130 is in the 81st percentile among its peer group of 21,951 CVEs.

Social Chatter

No social media mentions found for this CVE.

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.0 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (5)

composerpatch availablevia ghsa
Product: symfony/http-foundationFixed in: 4.4.7
composerpatch availablevia ghsa
Product: symfony/http-foundationFixed in: 5.0.7
composerpatch availablevia ghsa
Product: symfony/symfonyFixed in: 4.4.7
composerpatch availablevia ghsa
Product: symfony/symfonyFixed in: 5.0.7
github_advisorypatch availablevia nvd_reference
View patch

Vendor Advisories (1)

composerGHSA-mcx4-f5f5-4859low

Prevent cache poisoning via a Response Content-Type header in Symfony

Mar 30, 2020

References

github.com / symfony/symfony/commit/dca343442e6a954f96a2609e7b4e9c21ed6d74e6
PatchThird Party Advisory
github.com / symfony/symfony/security/advisories/GHSA-mcx4-f5f5-4859
Third Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/C36JLPHUPKDFAX6D5WYFC4ALO2K7RDUQ
symfony.com / blog/cve-2020-5255-prevent-cache-poisoning-via-a-response-content-type-header
Third Party Advisory