CVE-2026-88899
Medium
Elevated severity or exploit probability.
CVSS base
9.8
CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS — probability of exploitation (30 days)
0.8%
55.1th percentile
CISA KEV
Not listed
Weakness / dates
CWE-73
Published 2026-09-10 · modified 2026-09-11
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.
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