How severe is CVE-2026-26978?

CVE-2026-26978 has a CVSS 4.0 base score of 8.6, rated high severity.

Is CVE-2026-26978 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-26978?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-26978 have an EU (EUVD) identifier?

Yes. CVE-2026-26978 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30810.

When was CVE-2026-26978 published?

CVE-2026-26978 was published on 2026-05-18 and last updated on 2026-06-17.

CVE-2026-26978

CVE-2026-26978 is a high-severity vulnerability with a CVSS 4.0 base score of 8.6. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-502.

Key facts

Severity: High (CVSS 4.0 base score 8.6)
EPSS exploit prediction: 1% (55th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-30810
Weakness: CWE-502
Published: 2026-05-18
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-26978?: 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.
How severe is CVE-2026-26978?: CVE-2026-26978 has a CVSS 4.0 base score of 8.6, rated high severity.
Is CVE-2026-26978 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (55th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-26978?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-26978 have an EU (EUVD) identifier?: Yes. CVE-2026-26978 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-30810.
When was CVE-2026-26978 published?: CVE-2026-26978 was published on 2026-05-18 and last updated on 2026-06-17.

References

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