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CVE-2019-18886

User enumeration leak using switch user functionality in Symfony

5.3 MediumFix available

An issue was discovered in Symfony 4.2.0 to 4.2.11 and 4.3.0 to 4.3.7. The ability to enumerate users was possible due to different handling depending on whether the user existed when making unauthorized attempts to use the switch users functionality. This is related to symfony/security.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
Low
Integrity
None
Availability
None

Exploit likelihood

1.55%Up 0.7 points since Apr 14, 2021
90%50%10%1%

What each source reports

NVD Score used 5.3

An issue was discovered in Symfony 4.2.0 to 4.2.11 and 4.3.0 to 4.3.7. The ability to enumerate users was possible due to different handling depending on whether the user existed when making unauthorized attempts to use the switch users functionality. This is related to symfony/security.

Record
CVE-2019-18886
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CVSS 2.0
5.0 MediumAV:N/AC:L/Au:N/C:P/I:N/A:N
Weakness
CWE-203
Updated
2026-11-02
CVE List No score

An issue was discovered in Symfony 4.2.0 to 4.2.11 and 4.3.0 to 4.3.7. The ability to enumerate users was possible due to different handling depending on whether the user existed when making unauthorized attempts to use the switch users functionality. This is related to symfony/security.

Record
CVE-2019-18886
Updated
2026-11-02
EUVDEUVD-2019-0777 No score

An issue was discovered in Symfony 4.2.0 to 4.2.11 and 4.3.0 to 4.3.7. The ability to enumerate users was possible due to different handling depending on whether the user existed when making unauthorized attempts to use the switch users functionality. This is related to symfony/security.

Record
EUVD-2019-0777
Updated
2026-11-03
GitHub AdvisoriesGHSA-4vpc-5jx4-cfqg 5.3

User enumeration leak using switch user functionality in Symfony

An issue was discovered in Symfony 4.2.0 to 4.2.11 and 4.3.0 to 4.3.7. The ability to enumerate users was possible due to different handling depending on whether the user existed when making unauthorized attempts to use the switch users functionality. This is related to symfony/security.

Record
GHSA-4vpc-5jx4-cfqg
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-200, CWE-203
Updated
2026-11-02
OSV 5.3

An issue was discovered in Symfony 4.2.0 to 4.2.11 and 4.3.0 to 4.3.7. The ability to enumerate users was possible due to different handling depending on whether the user existed when making unauthorized attempts to use the switch users functionality. This is related to symfony/security.

Record
CVE-2019-18886
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-02
OSVDEBIAN-CVE-2019-18886 5.3

An issue was discovered in Symfony 4.2.0 to 4.2.11 and 4.3.0 to 4.3.7. The ability to enumerate users was possible due to different handling depending on whether the user existed when making unauthorized attempts to use the switch users functionality. This is related to symfony/security.

Record
DEBIAN-CVE-2019-18886
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-02
OSVGHSA-4vpc-5jx4-cfqg 5.3

User enumeration leak using switch user functionality in Symfony

An issue was discovered in Symfony 4.2.0 to 4.2.11 and 4.3.0 to 4.3.7. The ability to enumerate users was possible due to different handling depending on whether the user existed when making unauthorized attempts to use the switch users functionality. This is related to symfony/security.

Record
GHSA-4vpc-5jx4-cfqg
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Weakness
CWE-200, CWE-203
Updated
2026-11-02
OSVUBUNTU-CVE-2019-18886 5.3

An issue was discovered in Symfony 4.2.0 to 4.2.11 and 4.3.0 to 4.3.7. The ability to enumerate users was possible due to different handling depending on whether the user existed when making unauthorized attempts to use the switch users functionality. This is related to symfony/security.

Record
UBUNTU-CVE-2019-18886
CVSS 3.1
5.3 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
symfony/security-http
Packagist
 4.1.0 up to 4.2.12
4.2.12
symfony/security-http
Packagist
 4.3.0 up to 4.3.8
4.3.8
symfony/symfony
Packagist
 4.1.0 up to 4.2.12
4.2.12
symfony/symfony
Packagist
 4.3.0 up to 4.3.8
4.3.8
symfony
Debian:12
 before 4.3.8+dfsg-1
4.3.8+dfsg-1
symfony
Debian:13
 before 4.3.8+dfsg-1
4.3.8+dfsg-1
symfony
Debian:14
 before 4.3.8+dfsg-1
4.3.8+dfsg-1
symfony
Debian:8
From an advisory covering 3 CVEs
 before 2.3.21+dfsg-4+deb8u6, plus listed versions
2.3.21+dfsg-42.3.21+dfsg-4+deb8u12.3.21+dfsg-4+deb8u22.3.21+dfsg-4+deb8u32.3.21+dfsg-4+deb8u42.3.21+dfsg-4+deb8u5
2.3.21+dfsg-4+deb8u6
symfony/security-http
Packagist
 4.1.0 up to 4.2.12, plus listed versions
v4.1.0v4.1.1v4.1.10v4.1.11v4.1.12
Show 23 moreShow less
v4.1.2v4.1.3v4.1.4v4.1.5v4.1.6v4.1.7v4.1.8v4.1.9v4.2.0v4.2.0-BETA1v4.2.0-BETA2v4.2.0-RC1v4.2.1v4.2.10v4.2.11v4.2.2v4.2.3v4.2.4v4.2.5v4.2.6v4.2.7v4.2.8v4.2.9
4.2.12
symfony/security-http
Packagist
 4.3.0 up to 4.3.8, plus listed versions
v4.3.0v4.3.1v4.3.2v4.3.3v4.3.4v4.3.5v4.3.6v4.3.7
4.3.8
symfony/symfony
Packagist
 4.1.0 up to 4.2.12, plus listed versions
v4.1.0v4.1.1v4.1.10v4.1.11v4.1.12
Show 24 moreShow less
v4.1.13v4.1.2v4.1.3v4.1.4v4.1.5v4.1.6v4.1.7v4.1.8v4.1.9v4.2.0v4.2.0-BETA1v4.2.0-BETA2v4.2.0-RC1v4.2.1v4.2.10v4.2.11v4.2.2v4.2.3v4.2.4v4.2.5v4.2.6v4.2.7v4.2.8v4.2.9
4.2.12
symfony/symfony
Packagist
 4.3.0 up to 4.3.8, plus listed versions
v4.3.0v4.3.1v4.3.2v4.3.3v4.3.4v4.3.5v4.3.6v4.3.7
4.3.8

History

History
RecordedChangedSources
affected, facts
affected
aliasesEUVD
first indexedCVE List, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2019-18886 is a medium vulnerability (CVSS 5.3) in Sensiolabs Symfony, published November 18, 2019. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.55%, the 75th percentile. Fixed in symfony/security-http 4.2.12.

References

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