CVE-2026-88899 json
knowns before 0.31.0 External Control of Agent Working Directory via x-opencode-directory Header
published 2026-09-10 59 d ago modified 2026-09-11 58 d ago also EUVD-2026-75579
- cvss
- 9.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.8%
- EPSS 0.8% chance of exploitation in 30 days, percentile 57%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- knowns-dev knowns 0.31.0
CISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- total
- Assessed
- 58 d ago
Exploit prediction
0.81% chance of exploitation in the next 30 days, higher than 57% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 9.3 | 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 |
| CNA | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| CNA | 4.0 | 9.3 | 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:X/V:X/RE:X/U:X |
Affected products
- knowns-dev knowns
Classification
- Weakness
-
- CWE-73 External Control of File Name or Path
References
-
github.com
/knowns-dev/knowns/commit/37db0561b37b48b8bd035a417d7f1da6258ae657
patch
-
github.com
/knowns-dev/knowns/security/advisories/GHSA-9h2q-r9fh-f98w
vendor-advisory
-
github.com
/knowns-dev/knowns/blob/v0.30.0/internal/server/server.go#L1283-L1296
technical-description
-
github.com
/knowns-dev/knowns/releases/tag/v0.31.0
release-notes
-
vulncheck.com
/advisories/knowns-before-0.31.0-external-control-of-agent-working-directory-via-x-opencode-directory-header
third-party-advisory
Sources
- CVE List CVE-2026-88899
- NVD CVE-2026-88899
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.