How severe is CVE-2018-12027?

CVE-2018-12027 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2018-12027 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2018-12027?

CVE-2018-12027 affects Phusion Passenger. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2018-12027?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2018-12027 published?

CVE-2018-12027 was published on 2018-06-17 and last updated on 2026-06-17.

CVE-2018-12027

CVE-2018-12027 is a high-severity vulnerability in Phusion Passenger with a CVSS 3.x base score of 8.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-200.

Key facts

Severity: High (CVSS 3.x base score 8.8)
CVSS v2: 6.5
EPSS exploit prediction: 1% (61st percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-200
Affected product: Phusion Passenger
Published: 2018-06-17
Last modified: 2026-06-17

Description

An Insecure Permissions vulnerability in SpawningKit in Phusion Passenger 5.3.x before 5.3.2 causes information disclosure in the following situation: given a Passenger-spawned application process that reports that it listens on a certain Unix domain socket, if any of the parent directories of said socket are writable by a normal user that is not the application's user, then that non-application user can swap that directory with something else, resulting in traffic being redirected to a non-application user's process through an alternative Unix domain socket.

Frequently asked questions

What is CVE-2018-12027?: An Insecure Permissions vulnerability in SpawningKit in Phusion Passenger 5.3.x before 5.3.2 causes information disclosure in the following situation: given a Passenger-spawned application process that reports that it listens on a certain Unix domain socket, if any of the parent directories of said socket are writable by a normal user that is not the application's user, then that non-application user can swap that directory with something else, resulting in traffic being redirected to a non-application user's process through an alternative Unix domain socket.
How severe is CVE-2018-12027?: CVE-2018-12027 has a CVSS 3.x base score of 8.8, rated high severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2018-12027 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (61st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2018-12027?: CVE-2018-12027 affects Phusion Passenger. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2018-12027?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2018-12027 published?: CVE-2018-12027 was published on 2018-06-17 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:phusion:passenger:*:*:*:*:*:*:*:*

More vulnerabilities in Phusion Passenger

CVE-2018-12026 — Critical (CVSS 9.8): During the spawning of a malicious Passenger-managed application, SpawningKit in Phusion Passenger 5.3.x before 5.3.2…
CVE-2018-12028 — High (CVSS 7.8): An Incorrect Access Control vulnerability in SpawningKit in Phusion Passenger 5.3.x before 5.3.2 allows a…
CVE-2016-10345 — High (CVSS 7.8): In Phusion Passenger before 5.1.0, a known /tmp filename was used during passenger-install-nginx-module execution,…
CVE-2012-6135 — High (CVSS 7.5): RubyGems passenger 4.0.0 betas 1 and 2 allows remote attackers to delete arbitrary files during the startup process.
CVE-2018-12029 — High (CVSS 7.0): A race condition in the nginx module in Phusion Passenger 3.x through 5.x before 5.3.2 allows local escalation of…
CVE-2025-26803 — Medium (CVSS 5.3): The http parser in Phusion Passenger 6.0.21 through 6.0.25 before 6.0.26 allows a denial of service during parsing of a…

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