CVE-2026-42796
CriticalExploitedArelle < 2.39.10 Unauthenticated RCE via /rest/configure
Published May 4, 2026 · Updated Aug 12, 2026
Key Facts
Patch immediately- CVE-2026-42796 is a critical-severity vulnerability (CVSS 9.2 v4) affecting Arelle (Workiva).
- It is exploited in the wild, listed in Industry KEV feed, CIRCL KEV since Sep 18, 2026. No public exploit code is known.
- EPSS estimates a 3.9% probability of exploitation in the next 30 days.
- Fixed versions are available, including Arelle 2.39.10.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v4
9.2
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
EPSS (30-day exploit likelihood)
3.9%
Higher than 90.0% of all scored CVEs
Exploited in the wild
Yes
2 catalog listings
Public exploit code
None known
Get the full CVE-2026-42796 brief as a PDF
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Description
Arelle before 2.39.10 contains an unauthenticated remote code execution vulnerability in the /rest/configure REST endpoint that accepts a plugins query parameter and forwards it to the plugin manager without authentication or authorization. Attackers can supply a URL to a malicious Python file through the plugins parameter, causing the Arelle webserver to download and execute the attacker-controlled code within the Arelle process with its privileges.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| Industry KEV feed | Sep 18, 2026 | n/a | Not reported |
| CIRCL KEV | Sep 18, 2026 | n/a | Not reported |
Required action: Apply remediations or mitigations per vendor instructions or discontinue use of the product if remediation or mitigations are unavailable.
Affected Products
2 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| ArelleWorkiva | See advisory | 2.39.10 |
Patched Releases
Arelle
2.39.10
Timeline
Publicly disclosed
May 4, 2026
Last updated
Aug 12, 2026
Added to Industry KEV feed
Sep 18, 2026
Added to CIRCL KEV
Sep 18, 2026
Weakness Type
- CWE-306 Missing Authentication for Critical Function
References
- advisoryhttps://github.com/CVEProject/cvelistV5/tree/main/cves/2026/42xxx/CVE-2026-42796.json
- advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2026-42796
- advisoryhttps://www.vulncheck.com/advisories/arelle-unauthenticated-rce-via-rest-configure
- patchhttps://github.com/Arelle/Arelle/releases/tag/2.39.10
- exploitVulnCheck exploitation report
FAQ
Common Questions.
Arelle before 2.39.10 contains an unauthenticated remote code execution vulnerability in the /rest/configure REST endpoint that accepts a plugins query parameter and forwards it to the plugin manager without authentication or authorization.
Affected: Arelle (Workiva). The full list is in the CVE brief.
It is exploited in the wild, listed in Industry KEV feed, CIRCL KEV since Sep 18, 2026.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including Arelle 2.39.10.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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