CVE-2026-77658 (GCVE-0-2026-77658)

Vulnerability from cvelistv5 – Published: 2026-08-26 12:10 – Updated: 2026-08-26 13:11
VLAI
Title
Dia: dia: stack buffer overflow in bus object via unvalidated handle count in project files
Summary
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
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
SSVC
Exploitation: poc Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-08-26 13:09 UTC
CWE
  • CWE-121 - Stack-based Buffer Overflow
Assigner
fedora CNA under the redhat root
CNA scorecard C 69/100 over 42 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
GNOME Dia Affected: 0 , ≤ 0.98.0 (semver)
guessed Create a notification for this product.
Date Public
2026-08-21 00:00
Credits
Red Hat would like to thank Robin "drzobin" Larsson for reporting this issue.
Show details on NVD website
To clipboard 

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