Vulnerability in Simstudioai Sim
CVE-2026-86115
Sim before 0.8.14 classifies tool requests as internal based on URL prefix matching without scheme normalization, skipping SSRF validation and minting internal authentication tokens. Authenticated workflow authors can bypass external URL validation by supplying paths starting with /api/ in HTTP blocks to reach internal-only endpoints like POST /api/function/execute.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.0 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:N/A:N.
EPSS exploit prediction
EPSS: 0.005 (41.6th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 42nd percentile — 41.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.005 · change: +0.002
Affected products
Weakness classification (CWE)
References
- github.com/geo-chen/oss/blob/main/sim.md (technical-description)
- github.com/simstudioai/sim (product)
- github.com/simstudioai/sim/blob/v0.8.13/apps/sim/lib/auth/hybrid.ts (technical-description)
- github.com/simstudioai/sim/blob/v0.8.13/apps/sim/tools/index.ts (technical-description)
- github.com/simstudioai/sim/pull/7179 (issue-tracking, patch)
- www.vulncheck.com/advisories/sim-before-0.8.14-confused-deputy-in-tool-url-rout… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-86115?
- CVE-2026-86115 is a medium-severity vulnerability in Simstudioai Sim, classified under Unintended Proxy or Intermediary (Confused Deputy). CVSS score: 5.0/10. Published 2026-09-05.
- How severe is CVE-2026-86115?
- Medium severity. CVSS v3 base score is 5.0 out of 10.