CyberSecBulletin
CVE-2024-40896NVD status: Analyzed

libxml2: Improper Restriction of XML External Entity Reference

Published Updated By the CyberSecBulletin desk

CVE-2024-40896 is a critical-severity improper restriction of XML external entity reference vulnerability in libxml2, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists versions 2.11.9, 2.12.9, 2.13.3 as the first without the flaw, so updating libxml2 to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 1.22% chance of exploitation within 30 days, higher than 69% of scored CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update libxml2 to 2.11.9 or 2.12.9 or 2.13.3, whichever matches your release line, or a later version.
  2. 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
Libxml2libxml22.11.0 up to, but not including, 2.11.9; 2.12.0 up to, but not including, 2.12.9; 2.13.0 up to, but not including, 2.13.32.11.9, 2.12.9, 2.13.3
NetAppHci Compute NodeNot specified in the recordNot stated
NetAppSolidfire & Hci Management NodeNot specified in the recordNot stated
NetAppSolidfire & Hci Storage NodeNot specified in the recordNot stated
NetAppH300s FirmwareNot specified in the recordNot stated
NetAppH410s FirmwareNot specified in the recordNot stated
NetAppH500s FirmwareNot specified in the recordNot stated
NetAppH700s FirmwareNot specified in the recordNot stated
NetAppH410c FirmwareNot specified in the recordNot 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
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
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:N/UI:N/S:U/C:N/I:H/A:H. Scored by CISA (ADP).

Official description

In libxml2 2.11 before 2.11.9, 2.12 before 2.12.9, and 2.13 before 2.13.3, the SAX parser can produce events for external entities even if custom SAX handlers try to override entity content (by setting "checked"). This makes classic XXE attacks possible.

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

The underlying weakness: Improper Restriction of XML External Entity Reference

The product processes an XML document that can contain XML entities with URIs that resolve to documents outside of the intended sphere of control, causing the product to embed incorrect documents into its output.

How developers prevent this class of flaw

  • Many XML parsers and validators can be configured to disable external entity expansion.

More Improper Restriction of XML External Entity Reference vulnerabilities (CWE-611)

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

Third-party and government advisories

Other references

Recent Improper Restriction of XML External Entity Reference vulnerabilities

Spotted an error? Tell us.