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

Why this deserves its current priority

CVSS is 9.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps knowns-dev/knowns (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
Package	Affected range	Fixed version
knowns-dev/knownsgeneric	>=0 <0.31.0	0.31.0

Recommended response

Check inventory. Check lockfiles and deployed manifests for knowns-dev/knowns.
Review the reported fix. Update knowns-dev/knowns to 0.31.0 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

Published upstream
Sep 10, 2026
Evidence: source:cvelist:source_dates:source-dates:record
Source modified
Sep 11, 2026
Evidence: source:cvelist:source_dates:source-dates:record
First seen by HOL
Sep 10, 2026

Sources and claim methodology

Upstream source 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.

Quoted source text, attributed separately from HOL analysis.

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

Key facts