Deserialization in Pyyaml
CVE-2019-20477
PyYAML 5.1 through 5.1.2 has insufficient restrictions on the load and load_all functions because of a class deserialization issue, e.g., Popen is a class in the subprocess module. NOTE: this issue exists because of an incomplete fix for CVE-2017-18342.
Vulnerability class: Insecure Deserialization
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.051 (92.1th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 92nd percentile — 92.1% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.052 · newest: 0.051 · change: -0.000
Affected products
- Pyyaml
- Fedoraproject Fedora — versions 30, 31
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/yaml/pyyaml/blob/master/CHANGES (Third Party Advisory, Release Notes)
- www.exploit-db.com/download/47655 (Exploit, VDB Entry, Third Party Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
Frequently asked questions
- What is CVE-2019-20477?
- CVE-2019-20477 is a critical-severity vulnerability in Pyyaml, classified under Deserialization of Untrusted Data. CVSS score: 9.8/10. Published 2020-02-19.
- How severe is CVE-2019-20477?
- Critical severity. CVSS v3 base score is 9.8 out of 10.
- Is CVE-2019-20477 known to be exploited?
- 4 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.