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CVE-2026-71513— NLTK 3.10.0 through 3.10.2 Remote Code Execution via AllowlistUnpickler Dotted-Name Bypass

Quick assessment

Affected
nltk nltk
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

NLTK 在 3.10.3 版本之前存在一个远程代码执行漏洞，该漏洞出现在 AllowlistUnpickler 中。该组件仅校验 pickle 模块的字符串，而未校验全局名称，攻击者可通过属性遍历解析带点号的名称，从而调用未被列入白名单命名空间的可执行对象。攻击者可以构造不可信的过渡解析器（transition-parser）模型，当 TransitionParser.parse 通过 allowlisted_pickle_load 加载该模型时，即可执行任意命令。

CVSS 8.8 · High EPSS 1.08% · P62

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 2

VendorProduct Version RangeStatus
nltk nltk 3.10.0< 3.10.3 affected
3.10.3 unaffected
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I. Basic Information for CVE-2026-71513

Vulnerability Information
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Vulnerability Title
NLTK 3.10.0 through 3.10.2 Remote Code Execution via AllowlistUnpickler Dotted-Name Bypass
Source: CVE Program / CVE List V5
Vulnerability Description
NLTK before 3.10.3 contains a remote code execution vulnerability in AllowlistUnpickler that validates only the pickle module string and not the global name, allowing attackers to resolve dotted names by attribute traversal to callables outside the allowlisted namespace. Attackers can craft untrusted transition-parser models that execute arbitrary commands when TransitionParser.parse loads the model through allowlisted_pickle_load.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
可信数据的反序列化
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
nltk nltk 3.10.0 ~ 3.10.3 -

II. Public POCs for CVE-2026-71513

# POC Description Source Link Shenlong Link
AI-Generated POC Verified env Premium
Reproduced successfully in a real sandbox · Below is the actual recording of building the environment and exploiting the vulnerability.
Success marker: VULNERABLE: RCE via malicious TransitionParser model — os.system ran during model load: PROOF_994959cc2e9e7e10 uid=0(root) gid=0(root) groups=0(root)
Reproduction recording is a Pro+ exclusive
Watch the full sandbox build + live exploit recording for this CVE. Limited-time ¥499/mo.
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claude_code · 10963 chars
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Vulnerability reproduction recording (real sandbox build + trigger, exclusive)
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III. Intelligence Information for CVE-2026-71513

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Patches & Fixes for CVE-2026-71513 (2)

Vendor Advisories for CVE-2026-71513 (1)

Other References for CVE-2026-71513 (1)

Same Patch Batch · nltk · 2026-08-22 · 12 CVEs total

CVE-2026-62388 7.5 HIGH NLTK before 3.10.0 Insecure Default Configuration pathsec
CVE-2026-62384 7.5 HIGH NLTK FramenetCorpusReader Symlink Sandbox Bypass before 3.10.2
CVE-2026-66393 7.5 HIGH NLTK before 3.9.4 Denial of Service via JSONTaggedDecoder
CVE-2026-63312 7.5 HIGH NLTK StreamBackedCorpusView Bypasses pathsec.ENFORCE Arbitrary File Read
CVE-2026-63310 7.1 HIGH NLTK before 3.9.3 Missing Post-Download Integrity Verification
CVE-2026-65915 6.5 MEDIUM NLTK before 3.10.0 Arbitrary File Read via FileSystemPathPointer
CVE-2026-70626 6.2 MEDIUM NLTK before 3.9.4 Symlink Escape via CorpusReader
CVE-2026-62385 5.9 MEDIUM NLTK 3.9.4 Path Traversal via FrameNet and NKJP Readers
CVE-2026-62383 5.5 MEDIUM nltk IPIPANCorpusReader Symlink Arbitrary File Read
CVE-2026-63311 5.3 MEDIUM NLTK before 3.10.0 SSRF via DNS Resolution Failure
CVE-2026-71514 2.5 LOW NLTK 3.9.4 through 3.10.2 Path Traversal via CrubadanCorpusReader pathsec Bypass

IV. Related Vulnerabilities

Same product: nltk
Same vendor: nltk
Same weakness: CWE-502

V. Comments for CVE-2026-71513

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