CVE-2026-77658 (GCVE-0-2026-77658)
Vulnerability from cvelistv5 – Published: 2026-08-26 12:10 – Updated: 2026-08-26 13:11
VLAI
EPSS
VEX
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)
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
References
4 references
| URL | Tags |
|---|---|
| https://access.redhat.com/security/cve/CVE-2026-77658 | vdb-entryx_refsource_REDHAT |
| https://bugzilla.redhat.com/show_bug.cgi?id=2520890 | issue-trackingx_refsource_REDHAT |
| https://gitlab.gnome.org/GNOME/dia/-/blob/master/… | |
| https://gitlab.gnome.org/GNOME/dia/-/issues/581 |
Impacted products
Date Public
2026-08-21 00:00
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Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
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- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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