Security readout for executives and security teams
Plain-English summary
CVE-2026-42796 lets an unauthenticated attacker run code on vulnerable Arelle webservers through the /rest/configure endpoint. If exposed, this can lead to full compromise of the Arelle process and potentially the host environment. Treat externally reachable instances as urgent.
Executive priority
Prioritize remediation immediately for internet-facing or broadly reachable Arelle servers. This is a critical unauthenticated RCE with high confidentiality, integrity, and availability impact. There is no cited evidence of active exploitation, but business risk is severe if exposed.
Technical view
Arelle before 2.39.10 allows unauthenticated access to /rest/configure. The endpoint accepts a plugins query parameter and passes it to the plugin manager, which can download and execute attacker-controlled Python code inside the Arelle process. CVSS is 9.8 with network attack vector and no privileges or user interaction required.
Likely exposure
Highest exposure is Arelle running as a webserver with REST access reachable from untrusted networks. Internal-only deployments still matter if attackers gain network foothold. Source data does not identify specific hosted services or default deployment prevalence.
Exploitation context
The sources describe unauthenticated remote code execution, but do not show CISA KEV listing or confirmed active exploitation. The low-complexity, network-reachable nature makes exploitation risk high for exposed vulnerable servers.
Researcher notes
Root issue is missing authentication/authorization on /rest/configure, mapped to CWE-306. The vulnerable flow passes the plugins parameter into plugin handling, enabling remote Python execution. Avoid relying only on perimeter assumptions; validate both version and endpoint reachability.
Mitigation direction
- Upgrade affected Arelle deployments to version 2.39.10 or vendor-recommended current release.
- Restrict access to Arelle REST interfaces from untrusted networks.
- Review vendor release notes and advisory details before deployment.
- If immediate upgrade is impossible, isolate the service and monitor closely.
Validation and detection
- Inventory systems running Arelle webserver components.
- Confirm installed Arelle version is 2.39.10 or vendor-approved fixed version.
- Check whether /rest/configure is reachable from untrusted networks.
- Review logs for unexpected REST configuration or plugin activity.
- Verify network controls limit REST access to trusted management paths.
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-306: Credential and account abuse lookup
Authentication and credential weaknesses can make valid-account abuse and credential telemetry useful review starting points. 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-2026-42796 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
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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
2 official scoresWe 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:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9VulnCheckCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N——VulnCheckVulnerability scoring details
Base CVSS 4.0 score
9.2CriticalVector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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/Arelle/Arelle/releases/tag/2.39.10CVE reference, VulnCheck · release-notes, patch
- https://github.com/Arelle/Arelle/pull/2320CVE reference, VulnCheck · issue-tracking
- https://www.vulncheck.com/advisories/arelle-unauthenticated-rce-via-rest-configureCVE reference, VulnCheck · third-party-advisory
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.
Missing Authentication for Critical Function
Missing Authentication for Critical Function represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.