Security readout for executives and security teams
Plain-English summary
CVE-2026-24687 lets an authenticated Umbraco backoffice user read files from the server on Linux or Mac installations using vulnerable Umbraco Forms versions. This is mainly a confidentiality risk. Umbraco Cloud is reported unaffected because it runs on Windows. Vendor-patched versions are available.
Executive priority
Prioritize patching for self-hosted Linux/Mac Umbraco Forms environments, especially where backoffice access is internet-reachable or shared broadly. Treat as a moderate-risk confidentiality issue, not a confirmed mass-exploitation event.
Technical view
Umbraco Forms versions 16.0.0 through before 16.4.1 and 17.0.0 through before 17.1.1 are affected by a CWE-22 path traversal issue. The vulnerability involves the export endpoint and the fileName parameter, allowing authenticated backoffice users to enumerate/traverse filesystem paths and read file contents on Linux/Mac deployments.
Likely exposure
Exposure is limited to organizations running Umbraco Forms 16 or 17 on Linux/Mac where attackers have valid backoffice access or can abuse compromised accounts. Umbraco Cloud users are stated as not affected. Public internet exposure of the backoffice increases practical risk.
Exploitation context
The source bundle does not report active exploitation, and KEV status is false. Exploitation requires network access, low privileges, and an authenticated backoffice user. Impact is high confidentiality loss, with no stated integrity or availability impact.
Researcher notes
Evidence is limited to the CVE record and GitHub advisory. The advisory names the vulnerable endpoint and parameter, affected versions, unaffected Cloud context, and mitigations. Do not assume Windows self-hosted impact beyond the source wording.
Mitigation direction
- Upgrade Umbraco Forms to 16.4.1 or 17.1.1.
- If upgrade is delayed, follow Umbraco’s WAF or reverse proxy guidance.
- Block traversal sequences in the export endpoint fileName parameter.
- Restrict Umbraco backoffice access to trusted IP ranges.
- Block /umbraco/forms/api/v1/export if the export feature is unnecessary.
Validation and detection
- Inventory Umbraco Forms deployments and identify Linux/Mac hosts.
- Confirm installed Umbraco Forms versions are not in affected ranges.
- Verify Umbraco Cloud-only environments are not incorrectly flagged.
- Review reverse proxy or WAF rules for vendor-recommended protections.
- Check backoffice access controls and trusted IP restrictions.
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-22: 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 lookupFile access behavior lookup
The CVE wording references file access or upload behavior, so file telemetry and web shell review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2026-24687 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
- Medium
- CVSS
- 6 (4.0)
- Known Exploited
- No
- Published
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/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.
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:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N——Primary CVE scoreVulnerability scoring details
Base CVSS 4.0 score
6MediumVector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/umbraco/Umbraco.Forms.Issues/security/advisories/GHSA-hm5p-82g6-m3xhCVE reference · x_refsource_CONFIRM
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 Limitation of a Pathname to a Restricted Directory ('Path Traversal')
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.