CVE intelligence and bounded remediation
CVE-2019-17020 — Mozilla Firefox security vulnerability
Medium
CVSS 6.5
If an XML file is served with a Content Security Policy and the XML file includes an XSL stylesheet, the Content Security Policy will not be applied to the contents of the XSL stylesheet. If the XSL sheet e.g. includes JavaScript, it would bypass any of the restrictions of the Content Security Policy applied to the XML document. This vulnerability affects Firefox < 72.
- Severity
- Medium
- CVSS
- 6.5 (3.1)
- Published
- 2020-01-08
- CISA KEV
- Not currently listed
- Ecosystem
- browser
- Weaknesses
- CWE-611
Affected products
- mozilla / firefox
- canonical / ubuntu_linux / 16.04
- canonical / ubuntu_linux / 18.04
- canonical / ubuntu_linux / 19.04
- canonical / ubuntu_linux / 19.10
Matched remediation archetype
XML external entity and unsafe XML processing
This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.
Check exposure
- Inventory XML parsers used by APIs, file imports, office or image formats, identity protocols, feeds, and background jobs.
- Determine whether document type declarations, external entities, XInclude, schemas, or network resolvers are enabled.
- Map parser filesystem and network access and the sensitivity of documents it processes.
Remediate safely
- Configure each parser to reject document type declarations and disable external entity, XInclude, and network resolution features.
- Prefer a data format or hardened parser that does not support external resolution, and apply input size and depth limits.
- Update affected XML libraries and centralize secure parser construction so callers cannot silently override it.
Authoritative sources
Complete CVE record and remediation plan
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