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Vulnerability details: VCID-ty4s-3zke-nka1
Vulnerability ID VCID-ty4s-3zke-nka1
Aliases CVE-2021-3842
GHSA-rqjh-jp2r-59cj
PYSEC-2022-5
Summary NLTK Vulnerable to REDoS
Status Published
Exploitability 0.5
Weighted Severity 8.0
Risk 4.0
Affected and Fixed Packages Package Details
Weaknesses (3)
CWE-1333 Inefficient Regular Expression Complexity
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
epss 0.0017 https://api.first.org/data/v1/epss?cve=CVE-2021-3842
epss 0.0017 https://api.first.org/data/v1/epss?cve=CVE-2021-3842
epss 0.0017 https://api.first.org/data/v1/epss?cve=CVE-2021-3842
epss 0.0017 https://api.first.org/data/v1/epss?cve=CVE-2021-3842
cvssv3.1_qr HIGH https://github.com/advisories/GHSA-rqjh-jp2r-59cj
cvssv3.1 7.5 https://github.com/nltk/nltk
cvssv4 8.7 https://github.com/nltk/nltk
generic_textual HIGH https://github.com/nltk/nltk
cvssv3.1 7.5 https://github.com/nltk/nltk/commit/2a50a3edc9d35f57ae42a921c621edc160877f4d
cvssv4 8.7 https://github.com/nltk/nltk/commit/2a50a3edc9d35f57ae42a921c621edc160877f4d
generic_textual HIGH https://github.com/nltk/nltk/commit/2a50a3edc9d35f57ae42a921c621edc160877f4d
cvssv3.1 7.5 https://github.com/nltk/nltk/pull/2906
cvssv4 8.7 https://github.com/nltk/nltk/pull/2906
generic_textual HIGH https://github.com/nltk/nltk/pull/2906
cvssv3.1 7.5 https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2022-5.yaml
cvssv4 8.7 https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2022-5.yaml
generic_textual HIGH https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2022-5.yaml
cvssv3.1 7.5 https://huntr.dev/bounties/761a761e-2be2-430a-8d92-6f74ffe9866a
cvssv4 8.7 https://huntr.dev/bounties/761a761e-2be2-430a-8d92-6f74ffe9866a
generic_textual HIGH https://huntr.dev/bounties/761a761e-2be2-430a-8d92-6f74ffe9866a
cvssv3.1 7.5 https://nvd.nist.gov/vuln/detail/CVE-2021-3842
cvssv4 8.7 https://nvd.nist.gov/vuln/detail/CVE-2021-3842
generic_textual HIGH https://nvd.nist.gov/vuln/detail/CVE-2021-3842
Reference id Reference type URL
https://api.first.org/data/v1/epss?cve=CVE-2021-3842
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-3842
https://github.com/nltk/nltk
https://github.com/nltk/nltk/commit/2a50a3edc9d35f57ae42a921c621edc160877f4d
https://github.com/nltk/nltk/pull/2906
https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2022-5.yaml
https://huntr.dev/bounties/761a761e-2be2-430a-8d92-6f74ffe9866a
1003142 https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1003142
CVE-2021-3842 https://nvd.nist.gov/vuln/detail/CVE-2021-3842
GHSA-rqjh-jp2r-59cj https://github.com/advisories/GHSA-rqjh-jp2r-59cj
USN-7365-1 https://usn.ubuntu.com/7365-1/
No exploits are available.
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://github.com/nltk/nltk
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:N/VI:N/VA:H/SC:N/SI:N/SA:N Found at https://github.com/nltk/nltk
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

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none

passive

active

high

low

none

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none

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none
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://github.com/nltk/nltk/commit/2a50a3edc9d35f57ae42a921c621edc160877f4d
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:N/VI:N/VA:H/SC:N/SI:N/SA:N Found at https://github.com/nltk/nltk/commit/2a50a3edc9d35f57ae42a921c621edc160877f4d
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

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passive

active

high

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none

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Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://github.com/nltk/nltk/pull/2906
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:N/VI:N/VA:H/SC:N/SI:N/SA:N Found at https://github.com/nltk/nltk/pull/2906
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

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none

high

low

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low

none
Vector: CVSS:3.0/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/nltk/PYSEC-2022-5.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:N/VI:N/VA:H/SC:N/SI:N/SA:N Found at https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2022-5.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

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Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H Found at https://huntr.dev/bounties/761a761e-2be2-430a-8d92-6f74ffe9866a
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:N/VI:N/VA:H/SC:N/SI:N/SA:N Found at https://huntr.dev/bounties/761a761e-2be2-430a-8d92-6f74ffe9866a
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

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low

none

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none
Vector: CVSS:3.0/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-2021-3842
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:N/VI:N/VA:H/SC:N/SI:N/SA:N Found at https://nvd.nist.gov/vuln/detail/CVE-2021-3842
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

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low

none
Exploit Prediction Scoring System (EPSS)
Percentile 0.3807
EPSS Score 0.0017
Published At June 11, 2026, 12:55 p.m.
Date Actor Action Source VulnerableCode Version
2026-06-11T20:27:29.551803+00:00 GHSA Importer Import https://github.com/advisories/GHSA-rqjh-jp2r-59cj 38.6.0