CyberSecBulletin
CVE-2023-50387NVD status: Modified

Enterprise Linux: Allocation of Resources Without Limits or Throttling

Published Updated By the CyberSecBulletin desk

CVE-2023-50387 is a high-severity allocation of resources without limits or throttling vulnerability in Enterprise Linux from Red Hat, 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 Enterprise Linux versions: 6.0; 7.0; 8.0, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 100% chance of exploitation within 30 days, which is in the top 0.01% of all scored CVEs.

Patch now

Exploitation in the next 30 days is more likely than not, according to EPSS.

What to do

  1. Update Dnsmasq to 2.90 or a later version.
  2. Update Knot Resolver to 5.71 or a later version.
  3. Update Recursor to 4.8.6 or 4.9.3 or 5.0.2, whichever matches your release line, or a later version.
  4. Read the advisory on docs.powerdns.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
Red HatEnterprise Linux6.0; 7.0; 8.0; 9.0Not stated
MicrosoftWindows Server 2008r2Not stated
MicrosoftWindows Server 2012r2Not stated
MicrosoftWindows Server 2016Not specified in the recordNot stated
MicrosoftWindows Server 2019Not specified in the recordNot stated
MicrosoftWindows Server 2022Not specified in the recordNot stated
MicrosoftWindows Server 2022 23h2Not specified in the recordNot stated
Fedora ProjectFedora39Not stated
ThekelleysDnsmasqbefore 2.902.90
NicKnot Resolverbefore 5.715.71
PowerdnsRecursor4.8.0 up to, but not including, 4.8.6; 4.9.0 up to, but not including, 4.9.3; 5.0.0 up to, but not including, 5.0.24.8.6, 4.9.3, 5.0.2
ISCBind9.0.0 through 9.16.46; 9.18.0 through 9.18.22; 9.19.0 through 9.19.20Not stated
NlnetlabsUnboundbefore 1.19.11.19.1

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.

Scoring systemScoreSeverityScored by
CVSS 3.17.5HighNVD
CVSS 3.17.5HighCISA (ADP)

Official description

Certain DNSSEC aspects of the DNS protocol (in RFC 4033, 4034, 4035, 6840, and related RFCs) allow remote attackers to cause a denial of service (CPU consumption) via one or more DNSSEC responses, aka the "KeyTrap" issue. One of the concerns is that, when there is a zone with many DNSKEY and RRSIG records, the protocol specification implies that an algorithm must evaluate all combinations of DNSKEY and RRSIG records.

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

The underlying weakness: Allocation of Resources Without Limits or Throttling

The product allocates a reusable resource or group of resources on behalf of an actor without imposing any intended restrictions on the size or number of resources that can be allocated.

How developers prevent this class of flaw

  • Clearly specify the minimum and maximum expectations for capabilities, and dictate which behaviors are acceptable when resource allocation reaches limits.
  • Limit the amount of resources that are accessible to unprivileged users. Set per-user limits for resources. Allow the system administrator to define these limits. Be careful to avoid CWE-410.
  • 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 Allocation of Resources Without Limits or Throttling vulnerabilities (CWE-770)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other references

Other vulnerabilities in Enterprise Linux

All Enterprise Linux vulnerabilities

Recent Allocation of Resources Without Limits or Throttling vulnerabilities

Spotted an error? Tell us.