CVE-2026-86439: high-severity vulnerability in knowns-dev knowns
knowns before 0.30.0 Path Traversal via MCP doc and memory tools
Published · Updated
E-mail alert when it lands in KEV, gets a public PoC or its score goes up.
21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 8.7epss 1.1%
knowns versions before 0.30.0 fail to validate filesystem paths in MCP tool arguments, allowing attackers to read, create, overwrite and delete files outside the project directory. Attackers can supply path arguments containing directory traversal sequences to access arbitrary Markdown files accessible to the server process.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Affected products
knowns-dev · knownsRelated CVEs — knowns-dev knowns
In the same product, most dangerous first.
CVE-2026-86538HIGHknowns before 0.30.0 Path Traversal via templateFile parameterEPSS 1.0%CVE-2026-86543CRITICALknowns before 0.30.0 Unauthenticated Management API ExposureEPSS 0.9%CVE-2026-88899CRITICALknowns before 0.31.0 External Control of Agent Working Directory via x-opencode-directory HeaderEPSS 0.8%CVE-2026-86541HIGHknowns before 0.30.0 Path Traversal via code.replace MCP actionEPSS 0.8%CVE-2026-86775HIGHknowns before 0.30.0 Path Traversal via Document APIEPSS 0.7%CVE-2026-86542HIGHknowns before 0.30.0 Path Traversal via Import NameEPSS 0.7%
References
https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/doc_store.go#L124-L129https://github.com/knowns-dev/knowns/blob/v0.29.1/internal/storage/memory_store.go#L203-L211https://github.com/knowns-dev/knowns/commit/09c5a96fd5817b941dc86669278c1a17db10ed4ehttps://github.com/knowns-dev/knowns/releases/tag/v0.30.0https://github.com/knowns-dev/knowns/security/advisories/GHSA-9gfj-28hw-jchphttps://www.vulncheck.com/advisories/knowns-before-0.30.0-path-traversal-via-mcp-doc-and-memory-tools