CVE-2021-21424: fedoraproject fedora
Vulnerability summary
CVE-2021-21424 is a medium (CVSS 5.3) vulnerability in fedoraproject fedora. EPSS estimates a 1.64% chance of exploitation in the next 30 days, higher than 76% of scored vulnerabilities.
Advisory lineage
Upstream 0 · Downstream 2 · Related 1Timeline
- 13-05-2021PublishedVulnerability first disclosed.
- 03-08-2024Last modifiedVulnerability information updated.
Description
Symfony is a PHP framework for web and console applications and a set of reusable PHP components. The ability to enumerate users was possible without relevant permissions due to different handling depending on whether the user existed or not when attempting to use the switch users functionality. We now ensure that 403s are returned whether the user exists or not if a user cannot switch to a user or if the user does not exist. The patch for this issue is available for branch 3.4.
CVSS metrics
5 scores · 4 sources · 2 versions- OSV · UbuntuEcosystem advisory · calculated5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- OSV · DebianEcosystem advisory · calculated5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
- NVDNIST5.3MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
EPSS trend
Probability
1.64%
Chance of exploitation in the next 30 days
Percentile
76%
Versus all other CVEs
30-day change
-0.07 pp
From 1.71% on 19-09-2026
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-200Exposure of Sensitive Information to an Unauthorized ActorThe product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.
- CWE-203Observable DiscrepancyThe product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.
Affected systems
Debian1 product
- symfony< 4.4.19+dfsg-2
Fedoraproject1 product
- fedoraEOL33 | 34
Sensiolabs1 product
- symfony≥ 2.8.0, < 3.4.48 | ≥ 4.0.0, < 4.4.23 | ≥ 5.0.0, < 5.2.8
Symfony1 product
- symfony≥ 2.8.0, < 3.4.48 | ≥ 4.0.0, < 4.4.23 | ≥ 5.0.0, < 5.2.8
Ubuntu1 product
- symfony< 3.4.6+dfsg-1ubuntu0.1+esm2 | < 4.3.8+dfsg-1ubuntu1+esm1
5 vendors · 5 products
References
13 links- github.com/symfony/symfony/commit/2a581d22cc621b33d5464ed65c4bc2057f72f011REPORTPatchThird Party Advisory
- lists.fedoraproject.org/archives/…Vendor Advisory
- lists.fedoraproject.org/archives/…Vendor Advisory
- lists.fedoraproject.org/archives/…Vendor Advisory
- lists.fedoraproject.org/archives/…Vendor Advisory
