Security readout for executives and security teams
Plain-English summary
Attackers can abuse iCAgenda’s attachment feature to place and run PHP code on a vulnerable Joomla site. This can enable complete website and server compromise, data theft, defacement, or service disruption without credentials or user interaction.
Executive priority
Act immediately. Identify every internet-facing Joomla deployment using iCAgenda, upgrade affected versions, and investigate for compromise. Because CISA lists the issue as known exploited, patching alone should not replace retrospective log and file review.
Technical view
CVE-2026-48939 is a CWE-434 unrestricted file-upload vulnerability affecting iCAgenda 3.2.1 through 4.0.7. Network-accessible attackers can upload arbitrary files through the attachment feature and achieve PHP execution. The supplied CVSS 4.0 score is 10.0.
Likely exposure
Internet-facing Joomla sites running iCAgenda versions 3.2.1 through 4.0.7 are the primary exposure. Risk is highest where the attachment feature is publicly reachable. The bundle marks other versions unaffected by default, but administrators should verify the installed branch and vendor guidance.
Exploitation context
CISA KEV inclusion supports active exploitation. The bundle also references a public exploit repository, increasing practical risk, although its reliability and scope were not independently assessed here. The CVSS vector indicates no privileges or user interaction are required.
Researcher notes
The stated flaw is an unrestricted attachment upload leading to PHP execution. Branch-specific changelogs identify 3.9.15 and 4.0.8 as patch points. The provided evidence does not describe vulnerable code paths, forensic indicators, or prerequisites beyond the attachment feature and CVSS metrics.
Mitigation direction
- Upgrade the 3.x branch to at least iCAgenda 3.9.15.
- Upgrade the 4.x branch to at least iCAgenda 4.0.8.
- If upgrading is delayed, obtain temporary mitigation guidance directly from iCAgenda.
- Treat exposed, vulnerable installations as potentially compromised and begin incident-response review.
Validation and detection
- Inventory Joomla sites and confirm the installed iCAgenda version.
- Verify the installed version is 3.9.15, 4.0.8, or a later vendor-supported release.
- Review attachment and web directories for unexpected PHP or recently uploaded files.
- Examine web and Joomla logs for suspicious attachment uploads and subsequent file access.
- Confirm the attachment feature is not exposed on any overlooked staging or legacy site.
Public sources used
The source record changed after analysis: Material source record changed after analysis.
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-434: File access and web shell behavior lookup
File traversal and upload weaknesses can lead teams to review file, web shell, execution, and collection telemetry. 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 lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-48939 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
- 10 (4.0)
- Known Exploited
- Yes
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:A/AU:Y/U:Red
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.
CISA KEV status
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:H/SI:H/SA:H/E:A/AU:Y/U:Red——JoomlaVulnerability scoring details
Base CVSS 4.0 score
10CriticalVector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:A/AU:Y/U:Red
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.
- Added to KEVCISA-ADP
CISA Known Exploited Vulnerabilities metadata lists this CVE as known exploited.
- ADP timelineCISA-ADP
CVE-2026-48939 added to CISA KEV
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
- 2026-07-10T00:00:00.000Z: CVE-2026-48939 added to CISA KEV
Source materials
- CVE List V5 sourceCVE List V5
- https://www.icagenda.com/CVE reference, Joomla · product
- https://mysites.guru/blog/icagenda-zero-day-file-upload-rce/CVE reference, CISA-ADP · third-party-advisory
- https://www.icagenda.com/docs/changelog/icagenda-3-9-15CVE reference, CISA-ADP · patch
- https://www.icagenda.com/docs/changelog/icagenda-4-0-8CVE reference, CISA-ADP · patch
- https://github.com/Polosss/By-Poloss..-..CVE-2026-48939CVE reference, CISA-ADP · exploit
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-48939CVE reference, CISA-ADP · government-resource
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.
Unrestricted Upload of File with Dangerous Type
Unrestricted Upload of File with Dangerous Type represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.