prosody: Improper Restriction of XML External Entity Reference
CVE-2022-0217 is a high-severity improper restriction of XML external entity reference vulnerability in prosody, 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. There is no confirmed exploitation so far. EPSS estimates a 5.16% chance of exploitation within 30 days, which is in the top 7.43% of all scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of prosody you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on prosody.im for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
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
- 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
It was discovered that an internal Prosody library to load XML based on libexpat does not properly restrict the XML features allowed in parsed XML data. Given suitable attacker input, this results in expansion of recursive entity references from DTDs (CWE-776). In addition, depending on the libexpat version used, it may also allow injections using XML External Entity References (CWE-611).
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
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Advisories
Third-party and government advisories
- bugzilla.redhat.com/show_bug.cgi?id=2040639Issue Tracking, Third Party Advisory
Other vulnerabilities in prosody
- 7.5 High severity
- 7.5 High severity
Recent Improper Restriction of XML External Entity Reference vulnerabilities
- 9.1 Critical severity
- 8.2 High severity
- 9.8 Critical severity
- 9.1 Critical severity
- 7.5 High severity
- 7.8 High severity
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