CyberSecBulletin
CVE-2023-24805NVD status: Modified

cups-filters: Improper Neutralization of Special Elements used in an OS Command

Published Updated By the CyberSecBulletin desk

CVE-2023-24805 is a high-severity improper neutralization of special elements used in an OS command vulnerability in cups-filters from OpenPrinting, with a CVSS 3.1 base score of 8.8 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected cups-filters versions: <= 2.0rc1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 3.7% chance of exploitation within 30 days, higher than 90% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of cups-filters you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on github.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
OpenPrintingcups-filters<= 2.0rc1Not stated
Fedora ProjectFedora37; 38Not stated
DebianDebian Linux10.0; 11.0Not stated

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.18.8HighCNA (github.com)
CVSS 3.18.8HighNVD

Official description

cups-filters contains backends, filters, and other software required to get the cups printing service working on operating systems other than macos. If you use the Backend Error Handler (beh) to create an accessible network printer, this security vulnerability can cause remote code execution. `beh.c` contains the line `retval = system(cmdline) >> 8;` which calls the `system` command with the operand `cmdline`. `cmdline` contains multiple user controlled, unsanitized values. As a result an attacker with network access to the hosted print server can exploit this vulnerability to inject system commands which are executed in the context of the running server. This issue has been addressed in commit `8f2740357` and is expected to be bundled in the next release. Users are advised to upgrade when possible and to restrict access to network printers in the meantime.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Neutralization of Special Elements used in an OS Command

The product constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command before it is sent to a downstream component.

How developers prevent this class of flaw

  • If at all possible, use library calls rather than external processes to recreate the desired functionality.
  • For any data that will be used to generate a command to be executed, keep as much of that data out of external control as possible. For example, in web applications, this may require storing the data locally in the session's state instead of sending it out to the client in a hidden form field.
  • For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.

More Improper Neutralization of Special Elements used in an OS Command vulnerabilities (CWE-78)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Third-party and government advisories

Recent Improper Neutralization of Special Elements used in an OS Command vulnerabilities

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