Phusion Passenger incorrect permission assignment

published 2018-06-21 8 y ago modified 2026-06-17 4 mo ago also GHSA-4284-jfhc-f854 , EUVD-2022-2266

cvss: 5.3; version 3.0, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.2%; EPSS 1.2% chance of exploitation in 30 days, percentile 67%
public exploits: 0; none known

An issue was discovered in switchGroup() in agent/ExecHelper/ExecHelperMain.cpp in Phusion Passenger before 5.3.2. The set of groups (gidset) is not set correctly, leaving it up to randomness (i.e., uninitialized memory) which supplementary groups are actually being set while lowering privileges.

Patch / fix

fixed in 2 links 1

rubygems passenger 5.3.2
phusion passenger 5.3.2

github.com/phusion/passenger@4e97fdb commit

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-2018-12615 updated 2026-01-13 cvss 5.3

passenger: privilege lowering in switchGroup() in agent/ExecHelper/ExecHelperMain.cpp

Red Hat Ceph Storage 1.3 rubygem-passenger, ruby193-rubygem-passenger
affected: no fix planned “Will not fix”
Red Hat Satellite 6 mod_passenger, rubygem-passenger, rubygem-passenger-native, rubygem-passenger-native-libs Red Hat Update Infrastructure 3 for Cloud Providers rubygem-passenger
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

1.18% chance of exploitation in the next 30 days, higher than 67% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
NVD	3.0	5.3	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
NVD	2.0	5.0	AV:N/AC:L/Au:N/C:N/I:P/A:N
GitHub	3.0	5.3	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem	package	affected	fixed in
rubygems	passenger	<5.3.2	5.3.2

Classification

Weakness

CWE-732 Incorrect Permission Assignment for Critical Resource

References

github.com /phusion/passenger/commit/4e97fdb86d0a0141ec9a052c6e691fcd07bb45c8
web, patch, third-party-advisory
nvd.nist.gov /vuln/detail/CVE-2018-12615
advisory
github.com /phusion/passenger
package
github.com /rubysec/ruby-advisory-db/blob/master/gems/passenger/CVE-2018-12615.yml
web

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.

Summary