Staging Environment: Content and features may be unstable or change without notice.
Search for vulnerabilities
Vulnerability details: VCID-tk2n-xsk7-aqb9
Vulnerability ID VCID-tk2n-xsk7-aqb9
Aliases CVE-2019-20477
GHSA-3pqx-4fqf-j49f
PYSEC-2020-176
Summary 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.
Status Published
Exploitability 0.5
Weighted Severity 9.0
Risk 4.5
Affected and Fixed Packages Package Details
Weaknesses (3)
CWE-502 Deserialization of Untrusted Data
CWE-937 OWASP Top Ten 2013 Category A9 - Using Components with Known Vulnerabilities
CWE-1035 OWASP Top Ten 2017 Category A9 - Using Components with Known Vulnerabilities
System Score Found at
cvssv3 9.8 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2019-20477.json
epss 0.00467 https://api.first.org/data/v1/epss?cve=CVE-2019-20477
epss 0.00467 https://api.first.org/data/v1/epss?cve=CVE-2019-20477
epss 0.00467 https://api.first.org/data/v1/epss?cve=CVE-2019-20477
epss 0.00467 https://api.first.org/data/v1/epss?cve=CVE-2019-20477
epss 0.00467 https://api.first.org/data/v1/epss?cve=CVE-2019-20477
epss 0.00467 https://api.first.org/data/v1/epss?cve=CVE-2019-20477
epss 0.00467 https://api.first.org/data/v1/epss?cve=CVE-2019-20477
epss 0.00467 https://api.first.org/data/v1/epss?cve=CVE-2019-20477
epss 0.00467 https://api.first.org/data/v1/epss?cve=CVE-2019-20477
epss 0.00467 https://api.first.org/data/v1/epss?cve=CVE-2019-20477
epss 0.00467 https://api.first.org/data/v1/epss?cve=CVE-2019-20477
epss 0.00467 https://api.first.org/data/v1/epss?cve=CVE-2019-20477
epss 0.00467 https://api.first.org/data/v1/epss?cve=CVE-2019-20477
epss 0.00467 https://api.first.org/data/v1/epss?cve=CVE-2019-20477
cvssv3.1 9.8 https://github.com/advisories/GHSA-3pqx-4fqf-j49f
cvssv3.1_qr CRITICAL https://github.com/advisories/GHSA-3pqx-4fqf-j49f
cvssv4 9.3 https://github.com/advisories/GHSA-3pqx-4fqf-j49f
generic_textual CRITICAL https://github.com/advisories/GHSA-3pqx-4fqf-j49f
cvssv3.1 9.8 https://github.com/pypa/advisory-database/tree/main/vulns/pyyaml/PYSEC-2020-176.yaml
cvssv4 9.3 https://github.com/pypa/advisory-database/tree/main/vulns/pyyaml/PYSEC-2020-176.yaml
generic_textual CRITICAL https://github.com/pypa/advisory-database/tree/main/vulns/pyyaml/PYSEC-2020-176.yaml
cvssv3.1 9.8 https://github.com/yaml/pyyaml
cvssv4 9.3 https://github.com/yaml/pyyaml
generic_textual CRITICAL https://github.com/yaml/pyyaml
cvssv3.1 9.8 https://github.com/yaml/pyyaml/blob/master/CHANGES
cvssv4 9.3 https://github.com/yaml/pyyaml/blob/master/CHANGES
generic_textual CRITICAL https://github.com/yaml/pyyaml/blob/master/CHANGES
cvssv3.1 9.8 https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/33VBUY73AA6CTTYL3LRWHNFDULV7PFPN
cvssv4 9.3 https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/33VBUY73AA6CTTYL3LRWHNFDULV7PFPN
generic_textual CRITICAL https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/33VBUY73AA6CTTYL3LRWHNFDULV7PFPN
cvssv3.1 9.8 https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/52N5XS73Z5S4ZN7I7R56ICCPCTKCUV4H
cvssv4 9.3 https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/52N5XS73Z5S4ZN7I7R56ICCPCTKCUV4H
generic_textual CRITICAL https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/52N5XS73Z5S4ZN7I7R56ICCPCTKCUV4H
cvssv3.1 9.8 https://nvd.nist.gov/vuln/detail/CVE-2019-20477
cvssv4 9.3 https://nvd.nist.gov/vuln/detail/CVE-2019-20477
generic_textual CRITICAL https://nvd.nist.gov/vuln/detail/CVE-2019-20477
cvssv3.1 9.8 https://www.exploit-db.com/download/47655
cvssv4 9.3 https://www.exploit-db.com/download/47655
generic_textual CRITICAL https://www.exploit-db.com/download/47655
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2019-20477.json
https://api.first.org/data/v1/epss?cve=CVE-2019-20477
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-20477
https://github.com/advisories/GHSA-3pqx-4fqf-j49f
https://github.com/pypa/advisory-database/tree/main/vulns/pyyaml/PYSEC-2020-176.yaml
https://github.com/yaml/pyyaml
https://github.com/yaml/pyyaml/blob/master/CHANGES
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/33VBUY73AA6CTTYL3LRWHNFDULV7PFPN
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/33VBUY73AA6CTTYL3LRWHNFDULV7PFPN/
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/52N5XS73Z5S4ZN7I7R56ICCPCTKCUV4H
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/52N5XS73Z5S4ZN7I7R56ICCPCTKCUV4H/
https://nvd.nist.gov/vuln/detail/CVE-2019-20477
https://www.exploit-db.com/download/47655
1806005 https://bugzilla.redhat.com/show_bug.cgi?id=1806005
RHSA-2020:4641 https://access.redhat.com/errata/RHSA-2020:4641
RHSA-2021:0420 https://access.redhat.com/errata/RHSA-2021:0420
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2019-20477.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Found at https://github.com/advisories/GHSA-3pqx-4fqf-j49f
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N Found at https://github.com/advisories/GHSA-3pqx-4fqf-j49f
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Found at https://github.com/pypa/advisory-database/tree/main/vulns/pyyaml/PYSEC-2020-176.yaml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N Found at https://github.com/pypa/advisory-database/tree/main/vulns/pyyaml/PYSEC-2020-176.yaml
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Found at https://github.com/yaml/pyyaml
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N Found at https://github.com/yaml/pyyaml
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Found at https://github.com/yaml/pyyaml/blob/master/CHANGES
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N Found at https://github.com/yaml/pyyaml/blob/master/CHANGES
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Found at https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/33VBUY73AA6CTTYL3LRWHNFDULV7PFPN
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N Found at https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/33VBUY73AA6CTTYL3LRWHNFDULV7PFPN
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Found at https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/52N5XS73Z5S4ZN7I7R56ICCPCTKCUV4H
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N Found at https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/52N5XS73Z5S4ZN7I7R56ICCPCTKCUV4H
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Found at https://nvd.nist.gov/vuln/detail/CVE-2019-20477
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N Found at https://nvd.nist.gov/vuln/detail/CVE-2019-20477
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Found at https://www.exploit-db.com/download/47655
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N Found at https://www.exploit-db.com/download/47655
Attack Vector (AV) Attack Complexity (AC) Attack Requirements (AT) Privileges Required (PR) User Interaction (UI) Vulnerable System Impact Confidentiality (VC) Vulnerable System Impact Integrity (VI) Vulnerable System Impact Availability (VA) Subsequent System Impact Confidentiality (SC) Subsequent System Impact Integrity (SI) Subsequent System Impact Availability (SA)

network

adjacent

local

physical

low

high

none

present

none

low

high

none

passive

active

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none

high

low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.64327
EPSS Score 0.00467
Published At April 1, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-04-01T12:42:15.448279+00:00 Pypa Importer Import https://github.com/pypa/advisory-database/blob/main/vulns/pyyaml/PYSEC-2020-176.yaml 38.0.0