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CVE-2026-63312— NLTK StreamBackedCorpusView Bypasses pathsec.ENFORCE Arbitrary File Read

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 3.10.0 版本之前存在一个任意本地文件读取漏洞，该漏洞位于 StreamBackedCorpusView 中。通过直接调用 builtins.open() 而非 pathsec.open()，攻击者可以绕过 pathsec.ENFORCE 机制。如果攻击者能够控制 fileid 参数，则无论 ENFORCE 设置如何，均可读取任意本地文件，包括敏感的系统文件和应用程序凭据。

CVSS 7.5 · High EPSS 0.66% · P48

Possible ATT&CK Techniques 1 AI

T1552.004 · Private Keys

Affected Version Matrix 2

VendorProduct Version RangeStatus
nltk nltk < 3.10.0 affected
3.10.0 unaffected
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I. Basic Information for CVE-2026-63312

Vulnerability Information
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Vulnerability Title
NLTK StreamBackedCorpusView Bypasses pathsec.ENFORCE Arbitrary File Read
Source: CVE Program / CVE List V5
Vulnerability Description
NLTK before 3.10.0 contains an arbitrary local file read vulnerability in StreamBackedCorpusView that bypasses pathsec.ENFORCE by calling builtins.open() directly instead of pathsec.open(). Attackers who control the fileid argument can read arbitrary local files regardless of the ENFORCE setting, including sensitive system files and application credentials.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
对路径名的限制不恰当(路径遍历)
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
nltk nltk 0 ~ 3.10.0 -

II. Public POCs for CVE-2026-63312

# POC Description Source Link Shenlong Link
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Reproduced successfully in a real sandbox · Below is the actual recording of building the environment and exploiting the vulnerability.
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claude_code · 8154 chars
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100+ AI POC generations per month

III. Intelligence Information for CVE-2026-63312

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Vendor Advisories for CVE-2026-63312 (2)

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

CVE-2026-71513 8.8 HIGH NLTK 3.10.0 through 3.10.2 Remote Code Execution via AllowlistUnpickler Dotted-Name Bypass
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-2026-63310 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-22

V. Comments for CVE-2026-63312

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