CVE-2019-18886

NameCVE-2019-18886
DescriptionAn 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.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
ReferencesDLA-1999-1
NVD severitymedium

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
symfony (PTS)jessie2.3.21+dfsg-4+deb8u3vulnerable
jessie (security)2.3.21+dfsg-4+deb8u6fixed
stretch2.8.7+dfsg-1.3+deb9u2fixed
stretch (security)2.8.7+dfsg-1.3+deb9u3fixed
buster3.4.22+dfsg-2fixed
buster (security)3.4.22+dfsg-2+deb10u1fixed
bullseye, sid4.3.8+dfsg-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
symfonysource(unstable)4.3.8+dfsg-1
symfonysourcebuster(not affected)
symfonysourcejessie2.3.21+dfsg-4+deb8u6DLA-1999-1
symfonysourcestretch(not affected)

Notes

[buster] - symfony <not-affected> (Vulnerability introduced in 4.1.0)
[stretch] - symfony <not-affected> (Vulnerability introduced in 4.1.0)
https://symfony.com/blog/cve-2019-18886-prevent-user-enumeration-using-switch-user-functionality
Introduced by: https://github.com/symfony/symfony/commit/6e6ac9eaeec9e6a6cc0ab003cac3738460542b0a (v4.1.0-BETA1)
Previous versions asserts "the current user is granted to switch" BEFORE
"loading the user" and thus are not affected.
Fixed by: https://github.com/symfony/symfony/commit/7bd4a92fc9cc15d9a9fbb9eb1041e01b977f8332 (v4.2.12)

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