{"id":"UBUNTU-CVE-2026-77658","details":"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-\u003enum_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","modified":"2026-09-02T19:36:34.331426294Z","published":"2026-08-26T13:19:00Z","upstream":["CVE-2026-77658"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-77658"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-77658"},{"type":"REPORT","url":"https://gitlab.gnome.org/GNOME/dia/-/issues/581"}],"affected":[{"package":{"name":"dia","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/dia?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.97.3-1"],"ecosystem_specific":{"binaries":[{"binary_version":"0.97.3-1","binary_name":"dia"},{"binary_version":"0.97.3-1","binary_name":"dia-common"},{"binary_version":"0.97.3-1","binary_name":"dia-gnome"},{"binary_name":"dia-libs","binary_version":"0.97.3-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-77658.json"}},{"package":{"name":"dia","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/dia?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.97.3+git20160930-6","0.97.3+git20160930-7","0.97.3+git20160930-8"],"ecosystem_specific":{"binaries":[{"binary_name":"dia","binary_version":"0.97.3+git20160930-8"},{"binary_version":"0.97.3+git20160930-8","binary_name":"dia-common"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-77658.json"}},{"package":{"name":"dia","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/dia?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.97.3+git20160930-8.1","0.97.3+git20160930-8.2","0.97.3+git20160930-9"],"ecosystem_specific":{"binaries":[{"binary_name":"dia","binary_version":"0.97.3+git20160930-9"},{"binary_version":"0.97.3+git20160930-9","binary_name":"dia-common"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-77658.json"}},{"package":{"name":"dia","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/dia?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.97.3+git20160930-9","0.97.3+git20160930-9build1"],"ecosystem_specific":{"binaries":[{"binary_name":"dia","binary_version":"0.97.3+git20160930-9build1"},{"binary_version":"0.97.3+git20160930-9build1","binary_name":"dia-common"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-77658.json"}},{"package":{"name":"dia","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/dia?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.97.3+git20220525-5build1","0.97.3+git20220525-5build2","0.97.3+git20220525-5build3","0.98+git20240130-1","0.98+git20240130-1build2","0.98+git20240130-1build3","0.98+git20240130-1build4"],"ecosystem_specific":{"binaries":[{"binary_name":"dia","binary_version":"0.98+git20240130-1build4"},{"binary_name":"dia-common","binary_version":"0.98+git20240130-1build4"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-77658.json"}},{"package":{"name":"dia","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/dia?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["0.98+git20250902-0ubuntu1","0.98+git20250902-0ubuntu2","0.98+git20260221-1"],"ecosystem_specific":{"binaries":[{"binary_name":"dia","binary_version":"0.98+git20260221-1"},{"binary_version":"0.98+git20260221-1","binary_name":"dia-common"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-77658.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H"},{"type":"Ubuntu","score":"medium"}]}