OWSLib: Improper Restriction of XML External Entity Reference
CVE-2023-27476 is a high-severity improper restriction of XML external entity reference vulnerability in OWSLib from Geopython, 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 OWSLib versions: < 0.28.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.98% chance of exploitation within 30 days, higher than 63% of scored CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of OWSLib you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com 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
- HighAll data handled by the component can be read.
- Integrity
- NoneNothing can be modified.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.2 | High | CNA (github.com) |
| CVSS 3.1 | 7.5 | High | NVD |
Official description
OWSLib is a Python package for client programming with Open Geospatial Consortium (OGC) web service interface standards, and their related content models. OWSLib's XML parser (which supports both `lxml` and `xml.etree`) does not disable entity resolution, and could lead to arbitrary file reads from an attacker-controlled XML payload. This affects all XML parsing in the codebase. This issue has been addressed in version 0.28.1. All users are advised to upgrade. The only known workaround is to patch the library manually. See `GHSA-8h9c-r582-mggc` for details.
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.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Patches and release notes
Other references
Recent Improper Restriction of XML External Entity Reference vulnerabilities
- 7.7 High severity
- 9.8 Critical severity
- 8.8 High severity
- 9.1 Critical severity
- 8.1 High severity
- 7.4 High severity
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