What’s Vulnerable › Vulnerabilities

CVE-2026-88899: knowns before 0.31.0 External Control of Agent Working Directory via x-opencode-directory Header

• Severity: critical (CVSS 9.8 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.8% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-10 · updated 2026-09-11
• Weakness: CWE-73

Description

knowns versions before 0.31.0 fail to properly validate the x-opencode-directory request header in the /api/opencode proxy endpoint. Remote attackers can supply arbitrary directory paths to execute file operations outside the project root on the host system.

Affected products

• knowns-dev knowns: before 0.31.0 — fixed in 0.31.0

How to fix

Upgrade to a fixed version: knowns-dev knowns 0.31.0. Check the vendor advisory for mitigations.

References

• https://github.com/knowns-dev/knowns/blob/v0.30.0/internal/server/server.go#L1283-L1296
• https://github.com/knowns-dev/knowns/commit/37db0561b37b48b8bd035a417d7f1da6258ae657
• https://github.com/knowns-dev/knowns/releases/tag/v0.31.0
• https://github.com/knowns-dev/knowns/security/advisories/GHSA-9h2q-r9fh-f98w
• https://www.vulncheck.com/advisories/knowns-before-0.31.0-external-control-of-agent-working-directory-via-x-opencode-directory-header

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