CVE-2026-23740
Published: 06 February 2026
Summary
CVE-2026-23740 is a uncategorised-severity Uncontrolled Search Path Element (CWE-427) vulnerability in Sangoma Certified Asterisk. Its CVSS base score is 0.0.
Operationally, exploitation aligns with the MITRE ATT&CK technique Exploitation for Privilege Escalation (T1068); ranked at the 6.2th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.
The strongest mitigations our analysis identified are NIST 800-53 AC-6 (Least Privilege) and SI-2 (Flaw Remediation).
Deeper analysis
CVE-2026-23740 is a vulnerability in Asterisk, an open source private branch exchange and telephony toolkit. It affects the ast_coredumper component, which writes gdb init and output files to world-writable directories such as /tmp in versions prior to 20.7-cert9, 20.18.2, 21.12.1, 22.8.2, and 23.2.2. The flaw, classified as CWE-427 (Untrusted Search Path), allows manipulation of these file paths when the directory permits writes from unprivileged users.
Any local user on a Linux system with write access to the target directory, such as /tmp, can exploit the vulnerability. By controlling the gdb init file and output paths, the attacker can trick the root-privileged ast_coredumper into executing arbitrary commands or overwriting arbitrary files. The CVSS v3.1 base score is 0.0 (AV:L/AC:L/PR:N/UI:R/S:C/C:N/I:N/A:N), indicating a local attack with low complexity, no privileges required, user interaction needed, and changed scope but no direct confidentiality, integrity, or availability impact.
The official Asterisk security advisory at https://github.com/asterisk/asterisk/security/advisories/GHSA-xpc6-x892-v83c confirms the issue has been addressed in versions 20.7-cert9, 20.18.2, 21.12.1, 22.8.2, and 23.2.2. Practitioners should upgrade affected installations to these patched releases to prevent exploitation.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-5617
Vulnerability details
Asterisk is an open source private branch exchange and telephony toolkit. Prior to versions 20.7-cert9, 20.18.2, 21.12.1, 22.8.2, and 23.2.2, when ast_coredumper writes its gdb init and output files to a directory that is world-writable (for example /tmp), an attacker…
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with write permission(which is all users on a linux system) to that directory can cause root to execute arbitrary commands or overwrite arbitrary files by controlling the gdb init file and output paths. This issue has been patched in versions 20.7-cert9, 20.18.2, 21.12.1, 22.8.2, and 23.2.2.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise TechniquesAI
Why these techniques?
Local untrusted search path flaw in privileged ast_coredumper directly enables arbitrary command execution as root, mapping to exploitation for privilege escalation.
CVEs Like This One
Affected Assets
Mitigating Controls
Mitigating Controls (NIST 800-53 r5) AI
Directly requires applying the vendor patches (20.7-cert9 and later) that close the untrusted search path in ast_coredumper.
Requires ast_coredumper to execute with only the privileges needed to write core files, eliminating the ability for an unprivileged user to cause root-level command execution.
Enforces secure configuration settings such as a non-world-writable directory for gdb init/output files instead of /tmp.