Security readout for executives and security teams
Plain-English summary
A remote, unauthenticated caller can exploit how FreePBX records missed calls, potentially changing administrator accounts and taking control of the phone system. Exploitation requires a monitored extension to receive the crafted call and leave it unanswered. Successful compromise could expose communications, disrupt telephony, and corrupt the database.
Executive priority
Treat as an urgent remediation for affected, externally callable FreePBX systems. The low-complexity, unauthenticated path to administrator takeover creates material operational and confidentiality risk. Confirm exposure immediately and deploy the fixed module versions through normal change controls.
Technical view
The missedcall module inserts an inbound Caller ID name from a SIP From header into missedcalllog without escaping or bound parameters. This permits SQL injection in agi-bin/missedcallnotify.php when a monitored extension does not answer. The reported impact includes database corruption and modification of FreePBX administrator accounts for unauthorized remote access.
Likely exposure
FreePBX deployments using missedcall 16.0.0–16.0.10 or 17.0.1–17.0.3 are affected. Practical exposure is highest where untrusted inbound SIP calls can reach monitored extensions. The supplied sources do not establish how commonly the module or monitoring feature is enabled.
Exploitation context
The flaw is network-accessible, requires no authentication or user interaction, and is rated CVSS 4.0 9.3. The CVE is not listed as KEV in the supplied bundle, and no cited source confirms active exploitation. Absence from KEV does not prove exploitation is not occurring.
Researcher notes
CWE-89 applies. The vulnerable data flow is attacker-controlled SIP Caller ID name to a missedcalllog INSERT in missedcallnotify.php. Triggering depends on an unanswered call to a monitored extension. Supplied references include the vendor advisory and two remediation commits, but provide no confirmed exploitation telemetry.
Mitigation direction
- Upgrade missedcall to 16.0.11 or 17.0.4, matching the installed FreePBX branch.
- Prioritize internet-reachable or externally callable systems and those monitoring extensions for missed calls.
- Back up relevant configuration and data using established procedures before upgrading.
- If upgrading is delayed, consult the vendor advisory for supported protections; none are specified in the supplied sources.
Validation and detection
- Inventory FreePBX systems and record the installed missedcall module version.
- Confirm upgraded systems report missedcall 16.0.11, 17.0.4, or a later vendor-supported release.
- Identify whether untrusted inbound SIP calls can reach monitored extensions.
- Review administrator accounts for unexpected creation, modification, or access.
- Investigate database anomalies and missed-call activity around suspicious inbound Caller ID values.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-89: Database access and collection lookup
Injection into data stores can inform collection, data access, and exfiltration detection reviews. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupDatabase behavior lookup
The CVE wording references database injection or access, so collection and exfiltration review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-73663 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.3 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N——GitHub_MVulnerability scoring details
Base CVSS 4.0 score
9.3CriticalVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/FreePBX/security-reporting/security/advisories/GHSA-g27h-xf3q-h3rmCVE reference, GitHub_M · x_refsource_CONFIRM
- https://github.com/FreePBX/missedcall/commit/4ada1d6b280fc246e74babc8d52f4cd1509eff24CVE reference, GitHub_M · x_refsource_MISC
- https://github.com/FreePBX/missedcall/commit/710acdf51968db507b3f9c47ce3db006846cf44cCVE reference, GitHub_M · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection')
Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.