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CVE-2026-45699— Netatalk has Integer Underflow → Stack Buffer Overflow in copydir()

Quick assessment

Affected
Netatalk netatalk
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.

Netatalk是Netatalk团队开源的一个AFP文件服务器软件。 Netatalk 3.1.19版本至4.4.2版本存在数字错误漏洞，该漏洞源于afpd守护进程的copydir()函数中路径构造的剩余缓冲区大小计算存在整数下溢，可能导致栈缓冲区溢出，允许攻击者将文件名写入几乎已满的栈缓冲区。

CVSS 7.5 · High EPSS 0.45% · P37

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
Netatalk netatalk >= 3.1.19, < 4.4.3 affected
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I. Basic Information for CVE-2026-45699

Vulnerability Information
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Vulnerability Title
Netatalk has Integer Underflow → Stack Buffer Overflow in copydir()
Source: CVE Program / CVE List V5
Vulnerability Description
Netatalk is a Free and Open Source file server suite for Unix-like operating systems. In versions 3.1.19 through 4.4.2, a stack-based buffer overflow exists in the copydir() function of Netatalk's afpd daemon due to an integer underflow in the calculation of the remaining buffer size used for path construction. copydir() is a utility function called when a file operation crosses a device boundary inside an AFP shared volume, which the standard library's renameat() cannot handle. The function attempts to track available buffer space using srem and drem for source and destination paths. Incorrect arithmetic causes both srem and drem to underflow to SIZE_MAX. Consequently, boundary checks against strlen(de->d_name) always pass, allowing strcpy() to append filenames into nearly full stack buffers. Version 4.4.3 patches the issue. As a workaround, configure each AFP shared volume to be structured as a single file system, in other words no subdirectory of a shared volume should be a mount point for a different file system.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
整数下溢(超界折返)
Source: CVE Program / CVE List V5
Vulnerability Title
Netatalk 数字错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Netatalk是Netatalk团队开源的一个AFP文件服务器软件。 Netatalk 3.1.19版本至4.4.2版本存在数字错误漏洞，该漏洞源于afpd守护进程的copydir()函数中路径构造的剩余缓冲区大小计算存在整数下溢，可能导致栈缓冲区溢出，允许攻击者将文件名写入几乎已满的栈缓冲区。
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
Netatalk netatalk >= 3.1.19, < 4.4.3 -

II. Public POCs for CVE-2026-45699

# POC Description Source Link Shenlong Link
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Qwen3.6-35B-A3B · 11623 chars
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III. Intelligence Information for CVE-2026-45699

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Patches & Fixes for CVE-2026-45699 (1)

Vendor Advisories for CVE-2026-45699 (1)

IV. Related Vulnerabilities

Same product: netatalk
Same vendor: Netatalk
Same weakness: CWE-191

V. Comments for CVE-2026-45699

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