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CVE-2026-11940— tarfile extraction filter bypass allows escaping the destination directory

Quick assessment

Affected
Python Software Foundation CPython
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.

Python Software Foundation CPython是Python Software Foundation基金会的编程语言解释器。 Python Software Foundation CPython 存在安全漏洞，该漏洞源于tarfile.extractall()的'data'或'tar'过滤器可被绕过，其中提取回退在硬链接的较浅路径上重新创建了已验证的符号链接，导致相对目标可能逃逸目标目录，使恶意tar存档能创建指向目标外的符号链接，从而造成目录外文件读取或写入。

CVSS 7.8 · High EPSS 0.75% · P53

Possible ATT&CK Techniques 1 AI

T1059.004 · Unix Shell

Affected Version Matrix 6

VendorProduct Version RangeStatus
Python Software Foundation CPython < 3.10.21 affected
3.11.0< 3.11.16 affected
3.12.0< 3.12.14 affected
3.13.0< 3.13.15 affected
3.14.0< 3.14.7 affected
3.15.0a1< 3.15.0b4 affected
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I. Basic Information for CVE-2026-11940

Vulnerability Information
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Vulnerability Title
tarfile extraction filter bypass allows escaping the destination directory
Source: CVE Program / CVE List V5
Vulnerability Description
tarfile.extractall() with the 'data' or 'tar' filter could be bypassed by a crafted archive where a hardlink references a symlink stored at a deeper name than the hardlink itself.  The extraction fallback validated the symlink at it's archived location but recreated it at the hardlink's shallower path, letting a relative target the filter judged contained escape the destination directory.  This allowed a malicious tar archive to create a symlink pointing outside the destination, enabling out-of-destination file reads or writes. This was an incomplete fix of CVE-2025-4330.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA: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
Vulnerability Title
Python Software Foundation CPython 路径遍历漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Python Software Foundation CPython是Python Software Foundation基金会的编程语言解释器。 Python Software Foundation CPython 存在安全漏洞，该漏洞源于tarfile.extractall()的'data'或'tar'过滤器可被绕过，其中提取回退在硬链接的较浅路径上重新创建了已验证的符号链接，导致相对目标可能逃逸目标目录，使恶意tar存档能创建指向目标外的符号链接，从而造成目录外文件读取或写入。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Python Software Foundation CPython 0 ~ 3.10.21 -

II. Public POCs for CVE-2026-11940

# POC Description Source Link Shenlong Link
AI-Generated POC Premium
Qwen3.6-35B-A3B · 10004 chars
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III. Intelligence Information for CVE-2026-11940

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Patches & Fixes for CVE-2026-11940 (8)

Vendor Advisories for CVE-2026-11940 (1)

Mailing List Discussions for CVE-2026-11940 (1)

Same Patch Batch · Python Software Foundation · 2026-06-23 · 3 CVEs total

CVE-2026-11972 8.2 HIGH tarfile opened in streaming mode mishandles EOF
CVE-2026-0864 4.1 MEDIUM Configuration Injection via Carriage Return (\r) in write() method

IV. Related Vulnerabilities

Same product: CPython
Same vendor: Python Software Foundation
Same weakness: CWE-22

V. Comments for CVE-2026-11940

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