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Vulnerability details: VCID-gkzq-thjf-z7fa
Vulnerability ID VCID-gkzq-thjf-z7fa
Aliases CVE-2021-20270
GHSA-9w8r-397f-prfh
PYSEC-2021-140
Summary An infinite loop in SMLLexer in Pygments versions 1.5 to 2.7.3 may lead to denial of service when performing syntax highlighting of a Standard ML (SML) source file, as demonstrated by input that only contains the "exception" keyword.
Status Published
Exploitability 0.5
Weighted Severity 8.0
Risk 4.0
Affected and Fixed Packages Package Details
Weaknesses (3)
CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')
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 7.5 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-20270.json
epss 0.00089 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00089 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00089 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00089 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00089 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00089 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00089 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00089 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00089 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00089 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00089 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00089 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00089 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00089 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00089 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00115 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00115 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00115 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00115 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00115 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00115 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00115 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00115 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00115 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00119 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00119 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00119 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
epss 0.00119 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
cvssv3.1 7.5 https://bugzilla.redhat.com/show_bug.cgi?id=1922136
generic_textual HIGH https://bugzilla.redhat.com/show_bug.cgi?id=1922136
cvssv3.1 7.5 https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
cvssv3.1_qr HIGH https://github.com/advisories/GHSA-9w8r-397f-prfh
cvssv3.1 7.5 https://github.com/pygments/pygments
generic_textual HIGH https://github.com/pygments/pygments
cvssv3.1 7.5 https://github.com/pygments/pygments/commit/f91804ff4772e3ab41f46e28d370f57898700333
generic_textual HIGH https://github.com/pygments/pygments/commit/f91804ff4772e3ab41f46e28d370f57898700333
cvssv3.1 7.5 https://github.com/pypa/advisory-database/tree/main/vulns/pygments/PYSEC-2021-140.yaml
generic_textual HIGH https://github.com/pypa/advisory-database/tree/main/vulns/pygments/PYSEC-2021-140.yaml
cvssv3.1 7.5 https://lists.debian.org/debian-lts-announce/2021/05/msg00003.html
generic_textual HIGH https://lists.debian.org/debian-lts-announce/2021/05/msg00003.html
cvssv3.1 7.5 https://lists.debian.org/debian-lts-announce/2021/05/msg00006.html
generic_textual HIGH https://lists.debian.org/debian-lts-announce/2021/05/msg00006.html
cvssv2 5.0 https://nvd.nist.gov/vuln/detail/CVE-2021-20270
cvssv3.1 7.5 https://nvd.nist.gov/vuln/detail/CVE-2021-20270
generic_textual HIGH https://nvd.nist.gov/vuln/detail/CVE-2021-20270
archlinux Low https://security.archlinux.org/AVG-1662
archlinux Medium https://security.archlinux.org/AVG-1775
cvssv3.1 7.5 https://www.debian.org/security/2021/dsa-4889
generic_textual HIGH https://www.debian.org/security/2021/dsa-4889
cvssv3.1 7.5 https://www.oracle.com/security-alerts/cpuoct2021.html
generic_textual HIGH https://www.oracle.com/security-alerts/cpuoct2021.html
Reference id Reference type URL
https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-20270.json
https://api.first.org/data/v1/epss?cve=CVE-2021-20270
https://bugzilla.redhat.com/show_bug.cgi?id=1922136
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-20270
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-27291
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-30152
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-30154
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-30155
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-30157
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-30158
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-30159
https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.yaml
https://github.com/advisories/GHSA-9w8r-397f-prfh
https://github.com/pygments/pygments
https://github.com/pygments/pygments/commit/f91804ff4772e3ab41f46e28d370f57898700333
https://github.com/pypa/advisory-database/tree/main/vulns/pygments/PYSEC-2021-140.yaml
https://lists.debian.org/debian-lts-announce/2021/05/msg00003.html
https://lists.debian.org/debian-lts-announce/2021/05/msg00006.html
https://nvd.nist.gov/vuln/detail/CVE-2021-20270
https://www.debian.org/security/2021/dsa-4889
https://www.oracle.com/security-alerts/cpuoct2021.html
984664 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=984664
AVG-1662 https://security.archlinux.org/AVG-1662
AVG-1775 https://security.archlinux.org/AVG-1775
cpe:2.3:a:pygments:pygments:*:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:pygments:pygments:*:*:*:*:*:*:*:*
cpe:2.3:a:redhat:openshift_container_platform:3.11:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:redhat:openshift_container_platform:3.11:*:*:*:*:*:*:*
cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:redhat:openshift_container_platform:4.0:*:*:*:*:*:*:*
cpe:2.3:a:redhat:openstack_platform:10.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:redhat:openstack_platform:10.0:*:*:*:*:*:*:*
cpe:2.3:a:redhat:software_collections:-:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:a:redhat:software_collections:-:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:redhat:enterprise_linux:7.0:*:*:*:*:*:*:*
cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:* https://nvd.nist.gov/vuln/search/results?adv_search=true&isCpeNameSearch=true&query=cpe:2.3:o:redhat:enterprise_linux:8.0:*:*:*:*:*:*:*
RHSA-2021:0781 https://access.redhat.com/errata/RHSA-2021:0781
RHSA-2021:3252 https://access.redhat.com/errata/RHSA-2021:3252
RHSA-2021:4139 https://access.redhat.com/errata/RHSA-2021:4139
RHSA-2021:4150 https://access.redhat.com/errata/RHSA-2021:4150
RHSA-2021:4151 https://access.redhat.com/errata/RHSA-2021:4151
USN-4885-1 https://usn.ubuntu.com/4885-1/
USN-4897-2 https://usn.ubuntu.com/4897-2/
No exploits are available.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-20270.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:N/I:N/A:H Found at https://bugzilla.redhat.com/show_bug.cgi?id=1922136
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:N/I:N/A:H Found at https://ftp.suse.com/pub/projects/security/yaml/suse-cvss-scores.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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://github.com/pygments/pygments
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:N/I:N/A:H Found at https://github.com/pygments/pygments/commit/f91804ff4772e3ab41f46e28d370f57898700333
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:N/I:N/A:H Found at https://github.com/pypa/advisory-database/tree/main/vulns/pygments/PYSEC-2021-140.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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://lists.debian.org/debian-lts-announce/2021/05/msg00003.html
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:N/I:N/A:H Found at https://lists.debian.org/debian-lts-announce/2021/05/msg00006.html
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: AV:N/AC:L/Au:N/C:N/I:N/A:P Found at https://nvd.nist.gov/vuln/detail/CVE-2021-20270
Exploitability (E) Access Vector (AV) Access Complexity (AC) Authentication (Au) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

high

functional

unproven

proof_of_concept

not_defined

local

adjacent_network

network

high

medium

low

multiple

single

none

none

partial

complete

none

partial

complete

none

partial

complete
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://nvd.nist.gov/vuln/detail/CVE-2021-20270
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:N/I:N/A:H Found at https://www.debian.org/security/2021/dsa-4889
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:N/I:N/A:H Found at https://www.oracle.com/security-alerts/cpuoct2021.html
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
Exploit Prediction Scoring System (EPSS)
Percentile 0.26443
EPSS Score 0.00089
Published At July 30, 2025, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2025-07-31T08:11:22.542827+00:00 Pypa Importer Import https://github.com/pypa/advisory-database/blob/main/vulns/pygments/PYSEC-2021-140.yaml 37.0.0