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    CVE-2021-3828

    nltk is vulnerable to Inefficient Regular Expression Complexity

    Published:Sep 27, 2021
    Last Modified:Nov 21, 2024
    EPS:Sep 27, 2021
    EPSS Score:0.00433
    CVSS Score:7.5

    Affected Products

    Vendor
    Nltk
    Product
    Nltk

    Exploits

    https://huntr.dev/bounties/d19aed43-75bc-4a03-91a0-4d0bb516bc32https://huntr.dev/bounties/d19aed43-75bc-4a03-91a0-4d0bb516bc32

    Common Attack Pattern Enumeration and Classification (CAPEC)

    CAPEC-10 Buffer Overflow via Environment Variables
    CAPEC-120 Double Encoding
    CAPEC-14 Client-side Injection-induced Buffer Overflow
    CAPEC-15 Command Delimiters
    CAPEC-182 Flash Injection
    CAPEC-24 Filter Failure through Buffer Overflow
    CAPEC-267 Leverage Alternate Encoding
    CAPEC-3 Using Leading 'Ghost' Character Sequences to Bypass Input Filters
    CAPEC-41 Using Meta-characters in E-mail Headers to Inject Malicious Payloads
    CAPEC-43 Exploiting Multiple Input Interpretation Layers
    CAPEC-44 Overflow Binary Resource File
    CAPEC-45 Buffer Overflow via Symbolic Links
    CAPEC-46 Overflow Variables and Tags
    CAPEC-47 Buffer Overflow via Parameter Expansion
    CAPEC-492 Regular Expression Exponential Blowup
    CAPEC-52 Embedding NULL Bytes
    CAPEC-53 Postfix, Null Terminate, and Backslash
    CAPEC-6 Argument Injection
    CAPEC-64 Using Slashes and URL Encoding Combined to Bypass Validation Logic
    CAPEC-67 String Format Overflow in syslog()
    CAPEC-7 Blind SQL Injection
    CAPEC-71 Using Unicode Encoding to Bypass Validation Logic
    CAPEC-73 User-Controlled Filename
    CAPEC-78 Using Escaped Slashes in Alternate Encoding
    CAPEC-79 Using Slashes in Alternate Encoding
    CAPEC-8 Buffer Overflow in an API Call
    CAPEC-80 Using UTF-8 Encoding to Bypass Validation Logic
    CAPEC-88 OS Command Injection
    CAPEC-9 Buffer Overflow in Local Command-Line Utilities
    CAPEC-92 Forced Integer Overflow

    Related CVEs

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    CVE-2026-81724 (CVSS 6.9) — NLTK before 3.10.3 contains an uncontrolled recursion vulnerability in nltk.featstruct.FeatStructReader that a…
    CVE-2026-81723 (CVSS 6.3) — NLTK versions before 3.10.3 contain a quadratic CPU exhaustion vulnerability in XMLCorpusView._read_xml_fragme…
    CVE-2026-81722 (CVSS 8.7) — nltk PorterStemmer in versions <= 3.10.2 (fixed in 3.10.3) contains an inefficient-algorithmic-complexity deni…
    CVE-2026-80206 (CVSS 8.2) — NLTK before 3.10.3 contains a regular expression denial of service (ReDoS) vulnerability in the tgrep module. …
    CVE-2026-80205 (CVSS 8.7) — NLTK versions before 3.10.0 contain a regular expression denial of service vulnerability in Text.findall() and…
    CVE-2026-79676 (CVSS 8.2) — NLTK versions before 3.10.3 contain a path traversal vulnerability in corpus readers that reopen root-derived …
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    Common Vulnerability Scoring System

    Attack Vector
    Network
    Adjacent
    Local
    Physical
    Privileges Required
    None
    Low
    High
    User Interaction
    None
    Required
    Scope
    Unchanged
    Changed
    Confidentiality
    None
    Low
    High
    Integrity
    None
    Low
    High
    Availability
    None
    Low
    High