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CVE-2026-77658— Dia: dia: stack buffer overflow in bus object via unvalidated handle count in project files

Quick assessment

Affected
GNOME Dia
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.

GNOME Dia是GNOME基金会开源的一个图表绘制工具。 GNOME Dia 0.98.0及之前版本存在缓冲区错误漏洞，该漏洞源于在处理Dia XML项目文件中的Network Bus对象时，未验证bus_handles属性数量的上限，导致栈缓冲区溢出，可能造成栈溢出、SIGSEGV及栈帧/返回地址损坏。

CVSS 7.8 · High EPSS 0.20% · P9

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
GNOME Dia ≤ 0.98.0 affected
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I. Basic Information for CVE-2026-77658

Vulnerability Information
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Vulnerability Title
Dia: dia: stack buffer overflow in bus object via unvalidated handle count in project files
Source: CVE Program / CVE List V5
Vulnerability Description
A stack-based buffer overflow vulnerability exists in the Dia diagram editor when processing Network Bus objects from Dia XML project files. In objects/network/bus.c, bus_load() reads the number of bus handles from the file attribute "bus_handles" using attribute_num_data() without validating an upper bound: bus->num_handles = attribute_num_data(attr); When a bus handle is subsequently moved, bus_handle_moved() allocates two temporary arrays on the stack: parallel = (real *)g_alloca(num_handles * sizeof(real)); perp = (real *)g_alloca(num_handles * sizeof(real)); Because num_handles is fully attacker-controlled via the project file, sufficiently large values (for example 262144 or higher) cause g_alloca() to consume more stack space than the default thread stack limit (typically 8 MB on Linux), resulting in stack overflow, SIGSEGV, and potential stack frame / return-address corruption. An attacker can embed a Bus object with an excessive bus_handles count in a malicious .dia file. Exploitation requires the victim to open the file in Dia (file dialog, command line, or file association) and trigger handle manipulation (moving a bus handle), which exercises the vulnerable code path. The identical g_alloca pattern is present in objects/Misc/tree.c (copied from bus.c) and is likely vulnerable to the same class of attack via Tree objects. Affected versions: Dia 0.98.0 and earlier versions containing this code; issue confirmed on upstream master as of 2026-08-21. Upstream report: https://gitlab.gnome.org/GNOME/dia/-/issues/581
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
栈缓冲区溢出
Source: CVE Program / CVE List V5
Vulnerability Title
GNOME Dia 缓冲区错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
GNOME Dia是GNOME基金会开源的一个图表绘制工具。 GNOME Dia 0.98.0及之前版本存在缓冲区错误漏洞，该漏洞源于在处理Dia XML项目文件中的Network Bus对象时，未验证bus_handles属性数量的上限，导致栈缓冲区溢出，可能造成栈溢出、SIGSEGV及栈帧/返回地址损坏。
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
GNOME Dia 0 ~ 0.98.0 -

II. Public POCs for CVE-2026-77658

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III. Intelligence Information for CVE-2026-77658

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Vendor Advisories for CVE-2026-77658 (2)

Vendor Pages for CVE-2026-77658 (1)

Other References for CVE-2026-77658 (1)

Same Patch Batch · GNOME · 2026-08-26 · 3 CVEs total

CVE-2026-77652 7.8 HIGH Dia: dia: heap buffer overflow in wpg colormap parser via out-of-bounds palette index
CVE-2026-79902 5.5 MEDIUM Gimp: stack vla size underflow denial of service in seattle

IV. Related Vulnerabilities

Same product: Dia
Same vendor: GNOME
Same weakness: CWE-121

V. Comments for CVE-2026-77658

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