CyberSecBulletin
CVE-2022-29850NVD status: Modified

Various Lexmark products through 2022-04-27 allow an attacker who has already compromised an…

Published Updated By the CyberSecBulletin desk

CVE-2022-29850 is a high-severity improper input validation vulnerability in B2236 Firmware from Lexmark, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version mslsg.081.014 as the first without the flaw, so updating B2236 Firmware to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 1.1% chance of exploitation within 30 days, higher than 66% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update B2236 Firmware to mslsg.081.014 or a later version.
  2. Update Mb2236 Firmware to mxlsg.081.014 or a later version.
  3. Update Ms331 Firmware to mslbd.081.014 or a later version.
  4. Read the advisory on publications.lexmark.com for workarounds and exact fixed builds.
  5. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
LexmarkB2236 Firmwarebefore mslsg.081.014mslsg.081.014
LexmarkMb2236 Firmwarebefore mxlsg.081.014mxlsg.081.014
LexmarkMs331 Firmwarebefore mslbd.081.014mslbd.081.014
LexmarkMs431 Firmwarebefore mslbd.081.014mslbd.081.014
LexmarkM1342 Firmwarebefore mslbd.081.014mslbd.081.014
LexmarkB3442 Firmwarebefore mslbd.081.014mslbd.081.014
LexmarkB3340 Firmwarebefore mslbd.081.014mslbd.081.014
LexmarkXm1342 Firmwarebefore mslbd.081.014mslbd.081.014
LexmarkMx331 Firmwarebefore mxlbd.081.014mxlbd.081.014
LexmarkMx431 Firmwarebefore mxlbd.081.014mxlbd.081.014
LexmarkMb3442 Firmwarebefore mxlbd.081.014mxlbd.081.014
LexmarkMs321 Firmwarebefore msngm.081.014msngm.081.014
LexmarkMs421 Firmwarebefore msngm.081.014msngm.081.014
LexmarkMs521 Firmwarebefore msngm.081.014msngm.081.014
LexmarkMs621 Firmwarebefore msngm.081.014msngm.081.014
LexmarkM1242 Firmwarebefore msngm.081.014msngm.081.014
LexmarkM1246 Firmwarebefore msngm.081.014msngm.081.014
LexmarkB2338 Firmwarebefore msngm.081.014msngm.081.014
LexmarkB2442 Firmwarebefore msngm.081.014msngm.081.014
LexmarkB2546 Firmwarebefore msngm.081.014msngm.081.014
LexmarkB2650 Firmwarebefore msngm.081.014msngm.081.014
LexmarkMs622 Firmwarebefore mstgm.081.014mstgm.081.014
LexmarkM3250 Firmwarebefore mstgm.081.014mstgm.081.014
LexmarkMx321 Firmwarebefore mxngm.081.014mxngm.081.014
LexmarkMx421 Firmwarebefore mxtgm.081.014mxtgm.081.014

Version data comes from NVD's product matching; 35 further products are omitted here. 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
HighSuccess depends on conditions outside the attacker's control.
Privileges required
NoneNo account or login is needed.
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:H/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Official description

Various Lexmark products through 2022-04-27 allow an attacker who has already compromised an affected Lexmark device to maintain persistence across reboots.

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

The underlying weakness: Improper Input Validation

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

How developers prevent this class of flaw

  • Consider using language-theoretic security (LangSec) techniques that characterize inputs using a formal language and build recognizers for that language. This effectively requires parsing to be a distinct layer that effectively enforces a boundary between raw input and internal data representations, instead of allowing parser code to be scattered throughout the program, where it could be subject to errors or inconsistencies that create weaknesses.
  • Use an input validation framework such as Struts or the OWASP ESAPI Validation API. Note that using a framework does not automatically address all input validation problems; be mindful of weaknesses that could arise from misusing the framework itself (CWE-1173).
  • Understand all the potential areas where untrusted inputs can enter the product, including but not limited to: parameters or arguments, cookies, anything read from the network, environment variables, reverse DNS lookups, query results, request headers, URL components, e-mail, files, filenames, databases, and any external systems that provide data to the application. Remember that such inputs may be obtained indirectly through API calls.

More Improper Input Validation vulnerabilities (CWE-20)

Timeline

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

References

Recent Improper Input Validation vulnerabilities

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