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Full vulnerability report · 2026
CVE-2026-73664High confidence

FreePBX: Authenticated Arbitrary SSH Key Injection via Backup Module

FreePBX · backup

Official source article: GitHub GHSA-24W6-HPG3-RWFG ↗. Check the applicable product and release in the original source.

8.6HighCVSS 4.0
Recommended action
Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:High, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • EPSS is 0.51% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Monitor vendor guidance and exploitation sources for a material change.

Verification

  1. Confirm that the asset runs FreePBX backup and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 30 daysRemediation target: Within 180 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-58540

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

FreePBX is an open source IP PBX. From 17.0.5.34 until 17.0.11, the publicKeySave AJAX endpoint in Backup.class.php accepts an authenticated administrator's SSH public key and appends it to /home/asterisk/.ssh/authorized_keys for the asterisk system user without reliably enforcing backup-only command and source restrictions. The key grants persistent shell access that can execute arbitrary commands, access FreePBX and call data, modify system files, and disrupt services. This issue is fixed in version 17.0.11.

What

FreePBX is an open source IP PBX. From 17.0.5.34 until 17.0.11, the publicKeySave AJAX endpoint in Backup.class.php accepts an authenticated administrator's SSH public key and appends it to /home/asterisk/.ssh/authorized_keys for the asterisk system user without reliably enforcing backup-only command and source restrictions. The key grants persistent shell access that can execute arbitrary commands, access FreePBX and call data, modify system files, and disrupt services. This issue is fixed in version 17.0.11.

Why

The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

How

An attacker operating through a network path may attempt exploitation with elevated privileges. If successful, the issue may execute code or commands in the affected security context.

What

FreePBX is an open source IP PBX. From 17.0.5.34 until 17.0.11, the publicKeySave AJAX endpoint in Backup.class.php accepts an authenticated administrator's SSH public key and appends it to /home/asterisk/.ssh/authorized_keys for the asterisk system user without reliably enforcing backup-only command and source restrictions. The key grants persistent shell access that can execute arbitrary commands, access FreePBX and call data, modify system files, and disrupt services. This issue is fixed in version 17.0.11.

Why

The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

How

An attacker operating through a network path may attempt exploitation with elevated privileges. If successful, the issue may execute code or commands in the affected security context.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
None recorded

No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.

Likely attack path
a network path → Improper Privilege Management → execute code or commands in the affected security context
Attack surface
Network
Privileges required
High: elevated access is required
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-269 ↗

CWE-269: Improper Privilege Management. The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Common Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRHighPrivileges required: The attacker needs elevated or administrative privileges.UINoneUser interaction: No action by another user is required.VCHighVulnerable-system confidentiality: A successful attack can cause a major loss.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VAHighVulnerable-system availability: A successful attack can cause a major loss.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.
Post-exploitation / living off the land
After compromise, an attacker may use built-in shells, scripting engines, scheduled tasks and native network utilities for discovery, persistence or movement. This is a plausible LoTL path, not evidence that it has occurred for every attack.
NetworkRemote code executionCWE-269
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

Cyber Security Agency of Singapore · English · CSA-SB-20260819Security Bulletin 19 Aug 2026

The Cyber Security Agency of Singapore included this CVE in its official Security Bulletin 19 Aug 2026, published on 19 August 2026. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CSIRT Italia · Italian · rilevate-vulnerabilita-in-freepbxRilevate vulnerabilità in FreePBX

Rilevate sei vulnerabilità di cui due con gravità “critica” e sei con gravità "alta" in vari moduli di FreePBX, piattaforma open source per la configurazione e la gestione grafica di centralini telefonici basati su Asterisk. Tali vulnerabilità, qualora sfruttate, potrebbe consentire a un utente malintenzionato di eseguire codice arbitrario ed alterare i dati sui sistemi interessati.

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
backup: >= 17.0.5.34, < 17.0.11
Fixed
17.0.11.
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 13 Aug 2026 · Last source change 14 Aug 2026, 16:16 UTC · CWE-269 · Improper Privilege Management

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2026-58540
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD awaiting enrichment

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Affected versionsThe structured affected or fixed version information changed.
    Before
    >= 17.0.5.34, < 17.0.11 · Fixed: 17.0.11.
    After
    backup: >= 17.0.5.34, < 17.0.11 · Fixed: 17.0.11.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2026-58540↗CVE authority or vendor reference · GitHub GHSA-24W6-HPG3-RWFG↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-73664 · cve.blacktree.nl