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CVE-2026-6791— Potential stack-based buffer clash during tilde expansion in wordexp

Quick assessment

Affected
The GNU C Library glibc
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

GNU glibc是美国GNU基金会开源的一个 GNU 计划所实现的 C 标准库。 GNU glibc 2.0版本至2.43版本存在缓冲区错误漏洞，该漏洞源于在展开以波浪号加用户名开头的路径时，parse_tilde函数使用strndupa宏在栈上分配内存，未对用户输入的超长用户名进行边界检查，导致线程栈空间耗尽，从而触发栈冲突。

CVSS 6.6 · Medium EPSS 0.33% · P24

Possible ATT&CK Techniques 1 AI

T1203 · Exploitation for Client Execution

Affected Version Matrix 1

VendorProduct Version RangeStatus
The GNU C Library glibc 2.0≤ 2.43 affected
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I. Basic Information for CVE-2026-6791

Vulnerability Information
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Vulnerability Title
Potential stack-based buffer clash during tilde expansion in wordexp
Source: CVE Program / CVE List V5
Vulnerability Description
When expanding paths that begin with a tilde (~) followed by a username, the internal parse_tilde function extracts the username to determine the user's home directory. The implementation allocates memory for this username directly on the stack using the strndupa macro. Because the size of this allocation was determined by the length of the user-supplied input without any bounds checks, passing an excessively long username e.g. thousands of characters, forces the thread to exhaust its stack space. Thus if an application passes untrusted, attacker-controlled input to the wordexp function, an attacker can trigger a stack clash.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:H/SC:N/SI:L/SA:H/E:U
Source: CVE Program / CVE List V5
Vulnerability Type
栈缓冲区溢出
Source: CVE Program / CVE List V5
Vulnerability Title
GNU glibc 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
GNU glibc是美国GNU基金会开源的一个 GNU 计划所实现的 C 标准库。 GNU glibc 2.0版本至2.43版本存在缓冲区错误漏洞，该漏洞源于在展开以波浪号加用户名开头的路径时，parse_tilde函数使用strndupa宏在栈上分配内存，未对用户输入的超长用户名进行边界检查，导致线程栈空间耗尽，从而触发栈冲突。
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
The GNU C Library glibc 2.0 ~ 2.43 -

II. Public POCs for CVE-2026-6791

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III. Intelligence Information for CVE-2026-6791

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Vendor Advisories for CVE-2026-6791 (1)

IV. Related Vulnerabilities

Same product: glibc
Same vendor: The GNU C Library
Same weakness: CWE-121

V. Comments for CVE-2026-6791

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