CyberSecBulletin
CVE-2022-39028NVD status: Modified

Inetutils: NULL Pointer Dereference

Published Updated By the CyberSecBulletin desk

CVE-2022-39028 is a high-severity NULL pointer dereference vulnerability in Inetutils from GNU, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Inetutils versions: 2.3 and earlier. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 2.35% chance of exploitation within 30 days, higher than 84% of scored CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Check which version of Inetutils you run against the affected versions below, and install the vendor's latest release.
  2. Read the advisory on git.hadrons.org for workarounds and exact fixed builds.
  3. 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
GNUInetutils2.3 and earlierNot stated
MitKerberos 51.0.3 and earlierNot stated
DebianDebian Linux10.0Not stated
Netkit-telnet ProjectNetkit-telnet0.17 and earlierNot stated

Version data comes from NVD's product matching. 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
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
NoneNo data is disclosed.
Integrity
NoneNothing can be modified.
Availability
HighThe component can be taken down completely.

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

Official description

telnetd in GNU Inetutils through 2.3, MIT krb5-appl through 1.0.3, and derivative works has a NULL pointer dereference via 0xff 0xf7 or 0xff 0xf8. In a typical installation, the telnetd application would crash but the telnet service would remain available through inetd. However, if the telnetd application has many crashes within a short time interval, the telnet service would become unavailable after inetd logs a "telnet/tcp server failing (looping), service terminated" error. NOTE: MIT krb5-appl is not supported upstream but is shipped by a few Linux distributions. The affected code was removed from the supported MIT Kerberos 5 (aka krb5) product many years ago, at version 1.8.

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

The underlying weakness: NULL Pointer Dereference

The product dereferences a pointer that it expects to be valid but is NULL.

How developers prevent this class of flaw

  • For any pointers that could have been modified or provided from a function that can return NULL, check the pointer for NULL before use. When working with a multithreaded or otherwise asynchronous environment, ensure that proper locking APIs are used to lock before the check, and unlock when it has finished.
  • Select a programming language that is not susceptible to these issues.
  • Check the results of all functions that return a value and verify that the value is non-null before acting upon it.

More NULL Pointer Dereference vulnerabilities (CWE-476)

Timeline

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

References

Third-party and government advisories

Other vulnerabilities in Inetutils

All Inetutils vulnerabilities

Recent NULL Pointer Dereference vulnerabilities

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