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Vulnerability details: VCID-6mf3-qd5g-kuem
Vulnerability ID VCID-6mf3-qd5g-kuem
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 None
Weighted Severity None
Risk None
Affected and Fixed Packages Package Details
Weaknesses (1)
CWE-835 Loop with Unreachable Exit Condition ('Infinite Loop')
System Score Found at
cvssv3 7.5 https://access.redhat.com/hydra/rest/securitydata/cve/CVE-2021-20270.json
epss 0.00223 https://api.first.org/data/v1/epss?cve=CVE-2021-20270
cvssv3.1 7.5 https://bugzilla.redhat.com/show_bug.cgi?id=1922136
cvssv4 8.7 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 7.5 https://github.com/pygments/pygments
cvssv4 8.7 https://github.com/pygments/pygments
generic_textual HIGH https://github.com/pygments/pygments
cvssv3.1 7.5 https://github.com/pygments/pygments/commit/f91804ff4772e3ab41f46e28d370f57898700333
cvssv4 8.7 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
cvssv4 8.7 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
cvssv4 8.7 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
cvssv4 8.7 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
cvssv3.1 7.5 https://nvd.nist.gov/vuln/detail/CVE-2021-20270
cvssv4 8.7 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
cvssv4 8.7 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
cvssv4 8.7 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
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
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)

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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)

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Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N Found at https://bugzilla.redhat.com/show_bug.cgi?id=1922136
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)

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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)

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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)

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Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N Found at https://github.com/pygments/pygments
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)

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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)

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Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N Found at https://github.com/pygments/pygments/commit/f91804ff4772e3ab41f46e28d370f57898700333
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)

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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)

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Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N Found at https://github.com/pypa/advisory-database/tree/main/vulns/pygments/PYSEC-2021-140.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)

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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)

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Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N Found at https://lists.debian.org/debian-lts-announce/2021/05/msg00003.html
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)

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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)

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Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N Found at https://lists.debian.org/debian-lts-announce/2021/05/msg00006.html
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)

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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)

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Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N Found at https://nvd.nist.gov/vuln/detail/CVE-2021-20270
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)

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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)

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Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N Found at https://www.debian.org/security/2021/dsa-4889
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)

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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)

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Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N Found at https://www.oracle.com/security-alerts/cpuoct2021.html
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)

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Exploit Prediction Scoring System (EPSS)
Percentile 0.44929
EPSS Score 0.00223
Published At May 29, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-05-29T08:37:16.642013+00:00 Pypa Importer Import https://github.com/pypa/advisory-database/blob/main/vulns/pygments/PYSEC-2021-140.yaml 38.6.0