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Vulnerability record · CVE-2026-26978 · published 18 May 2026

CVE-2026-26978: Deserialization of untrusted data vulnerability

FreePBX is an open source IP PBX. In versions below 16.0.71 and 17.0.6, the backup module does not properly sanitize data during restore operations, potentially leading to compromise if the backup contains carefully crafted hostile data. During backup restore operations, FreePBX extracts selected files from a user-supplied tar archive. If a malicious file exists in the archive, it is read and passed directly to unserialize() without validation, class restrictions, or integrity checks. This issue allows Remote Code Execution during restoration of the backup as the web server user (typically asterisk or www-data). The attack does not require shell access, CLI access, or filesystem write permissions beyond the normal restore workflow. Authentication with a known username that has sufficient access permissions and/or write access to backup files is required. This issue has been fixed in versions 16.0.71 and 17.0.6.

8.6 CVSS 4.0 High EPSS 0.97% · top 39.8% CWE-502 · Deserialization of untrusted data Deferred
8.6CVSS 4.0 base score
0.97%EPSS exploitation probability, 30 days
NoNot in CISA KEV
0Affected product versions listed by NVD
3References
24 Jul 2026Last modified by NVD

Description

FreePBX is an open source IP PBX. In versions below 16.0.71 and 17.0.6, the backup module does not properly sanitize data during restore operations, potentially leading to compromise if the backup contains carefully crafted hostile data. During backup restore operations, FreePBX extracts selected files from a user-supplied tar archive. If a malicious file exists in the archive, it is read and passed directly to unserialize() without validation, class restrictions, or integrity checks. This issue allows Remote Code Execution during restoration of the backup as the web server user (typically asterisk or www-data). The attack does not require shell access, CLI access, or filesystem write permissions beyond the normal restore workflow. Authentication with a known username that has sufficient access permissions and/or write access to backup files is required. This issue has been fixed in versions 16.0.71 and 17.0.6.

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

LinkTags
https://github.com/FreePBX/backup/commit/45c57e1207cbf9fd1c5f76f8a3e72d204a69a472
https://github.com/FreePBX/backup/commit/64781af5c80cce0cff21a981be4d8e6a7a71f2c4
https://github.com/FreePBX/security-reporting/security/advisories/GHSA-5v7h-49gr-jcwr

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Source: NIST National Vulnerability Database (record CVE-2026-26978), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.