CVE-2023-34241

CUPS vulnerable to use-after-free in cupsdAcceptClient()

Published Jun 22, 2023 CVSS 3.1 · 5.3 Medium EPSS 1.4% KEV · Not listed
Description
OpenPrinting CUPS is a standards-based, open source printing system for Linux and other Unix-like operating systems. Starting in version 2.0.0 and prior to version 2.4.6, CUPS logs data of free memory to the logging service AFTER the connection has been closed, when it should have logged the data right before. This is a use-after-free bug that impacts the entire cupsd process.

The exact cause of this issue is the function `httpClose(con->http)` being called in `scheduler/client.c`. The problem is that httpClose always, provided its argument is not null, frees the pointer at the end of the call, only for cupsdLogClient to pass the pointer to httpGetHostname. This issue happens in function `cupsdAcceptClient` if LogLevel is warn or higher and in two scenarios: there is a double-lookup for the IP Address (HostNameLookups Double is set in `cupsd.conf`) which fails to resolve, or if CUPS is compiled with TCP wrappers and the connection is refused by rules from `/etc/hosts.allow` and `/etc/hosts.deny`.

Version 2.4.6 has a patch for this issue.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-3476-1 cups security update
EUVD EUVD EUVD-2023-38329 OpenPrinting CUPS is a standards-based, open source printing system for Linux and other Unix-like operating systems. Starting in version 2.0.0 and prior to version 2.4.6, CUPS logs data of free memory to the logging service AFTER the connection has been closed, when it should have logged the data right before. This is a use-after-free bug that impacts the entire cupsd process. The exact cause of this issue is the function `httpClose(con->http)` being called in `scheduler/client.c`. The problem is that httpClose always, provided its argument is not null, frees the pointer at the end of the call, only for cupsdLogClient to pass the pointer to httpGetHostname. This issue happens in function `cupsdAcceptClient` if LogLevel is warn or higher and in two scenarios: there is a double-lookup for the IP Address (HostNameLookups Double is set in `cupsd.conf`) which fails to resolve, or if CUPS is compiled with TCP wrappers and the connection is refused by rules from `/etc/hosts.allow` and `/etc/hosts.deny`. Version 2.4.6 has a patch for this issue.
Ubuntu USN Ubuntu USN USN-6184-1 CUPS vulnerability
Ubuntu USN Ubuntu USN USN-6184-2 CUPS vulnerability
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
GitHub_M
Published
Updated
Feb 13, 2025, 4:55 PM
Reserved
May 31, 2023, 1:51 PM
Status
Modified
Published
Jun 22, 2023, 11:15 PM
Modified
Jun 17, 2026, 6:03 AM
Severity
Moderate
Public date
Jun 22, 2023, 11:00 AM