# CVE-2026-86539 — knowns-dev knowns

> As of 2026-09-07, CVE-2026-86539 is a HIGH-severity vulnerability in knowns-dev knowns, CVSS v3.1 7.2, EPSS 0.2% (10.6th percentile). No Threadlinqs-tracked threat campaign has been attributed to CVE-2026-86539 as of 2026-09-07; the identifier is re-checked against the Threadlinqs threat corpus on every daily ingest.

**Last updated:** 2026-09-07

## What is CVE-2026-86539?

knowns through 0.33.0 contains a server-side request forgery vulnerability in the POST /api/embedding-models/test endpoint that issues outbound requests to caller-supplied destinations without validation. Attackers can enumerate internal hosts and cloud metadata endpoints by observing transport error messages that reveal network reachability information.

The record classifies CVE-2026-86539 under weakness class [CWE-918](https://intel.threadlinqs.com/cwe/CWE-918). Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 28 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 7.2 — HIGH (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N`)
- **CVSS v4.0 base score:** 6.9 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N`)
- **EPSS (FIRST):** 0.2% probability of exploitation in the next 30 days, higher than 10.6% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 4/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-09-07

## Is CVE-2026-86539 being exploited?

It currently carries a trending score of 32 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [knowns-dev](https://intel.threadlinqs.com/vendors/knowns-dev): knowns

## How to fix CVE-2026-86539

No vendor patch reference has been recorded for CVE-2026-86539 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-86539

No threat campaign in the Threadlinqs corpus currently references CVE-2026-86539, in its CVE list or as an indicator. The linkage is recomputed from the live corpus on every daily ingest, so this section fills in as soon as a tracked campaign cites the identifier.

## Sources

Enriched from CVE.org, NVD, GitHub Security Advisories, FIRST EPSS. Last verified by Threadlinqs on 2026-09-08. This product uses the NVD API but is not endorsed or certified by the NVD.

**Vendor advisory and patch**

- [github.com — vendor advisory](https://github.com/knowns-dev/knowns/security/advisories/GHSA-qx9v-m9gg-p5jg)

**Technical analysis**

- [github.com — technical description](https://github.com/knowns-dev/knowns/blob/v0.33.0/internal/server/routes/embedding_models.go#L64-L110)
- [github.com — technical description (imports)](https://github.com/knowns-dev/knowns/blob/v0.33.0/internal/server/routes/imports.go#L317-L330)

**Third-party advisory**

- [vulncheck.com — third party advisory](https://www.vulncheck.com/advisories/knowns-through-0.33.0-server-side-request-forgery-via-embedding-models-endpoint)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-86539
Full detection coverage and IOCs for threats exploiting CVE-2026-86539 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp