CyberSecBulletin
CVE-2022-48565NVD status: Modified

Python: Improper Restriction of XML External Entity Reference

Published Updated By the CyberSecBulletin desk

CVE-2022-48565 is a critical-severity improper restriction of XML external entity reference vulnerability in Python, with a CVSS 3.1 base score of 9.8 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 3.6.13, 3.7.10, 3.8.7 as the first without the flaw, so updating Python to one of those releases or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 5.23% chance of exploitation within 30 days, which is in the top 7.35% of all scored CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Python to 3.6.13 or 3.7.10 or 3.8.7 or 3.9.1, whichever matches your release line, or a later version.
  2. Read the advisory on bugs.python.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
PythonPythonbefore 3.6.13; 3.7.0 up to, but not including, 3.7.10; 3.8.0 up to, but not including, 3.8.7; 3.9.0 up to, but not including, 3.9.13.6.13, 3.7.10, 3.8.7, 3.9.1
DebianDebian Linux10.0Not 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
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:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Official description

An XML External Entity (XXE) issue was discovered in Python through 3.9.1. The plistlib module no longer accepts entity declarations in XML plist files to avoid XML vulnerabilities.

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: poc, automatable: yes, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Advisories

Third-party and government advisories

Other vulnerabilities in Python

All Python vulnerabilities

Recent Improper Restriction of XML External Entity Reference vulnerabilities

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