Vulnerability record · CVE-2026-88899 · published 10 September 2026

CVE-2026-88899: knowns versions before 0.31.0 fail to properly validate the x-opencode-directory request header in the /api/op…

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.

9.3 CVSS 4.0 Critical EPSS 0.81% · top 44.9% CWE-73 · CWE-73 Deferred

9.3CVSS 4.0 base score

0.81%EPSS exploitation probability, 30 days

NoNot in CISA KEV

0Affected product versions listed by NVD

5References

11 Sep 2026Last modified by NVD

Description

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:

References

Link	Tags
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-dir

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Source: NIST National Vulnerability Database (record CVE-2026-88899), CISA KEV, FIRST EPSS (scores of 2026-09-26). This page is refreshed as NVD updates the record.