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fix: skills CRUD broken on Windows due to hardcoded path separator #492

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Merged
Nikhil (shadowfax92) merged 1 commit into from
Mar 12, 2026
Merged

fix: skills CRUD broken on Windows due to hardcoded path separator #492

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4 changes: 2 additions & 2 deletions apps/server/src/skills/service.ts
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
import { mkdir, readFile, rm, stat, writeFile } from 'node:fs/promises'
import { join, resolve } from 'node:path'
import { join, resolve, sep } from 'node:path'
import matter from 'gray-matter'
import { getSkillsDir } from '../lib/browseros-dir'
import { logger } from '../lib/logger'
Expand All @@ -23,7 +23,7 @@ export function slugify(name: string): string {
function safeSkillDir(id: string): string {
const skillsDir = getSkillsDir()
const resolved = resolve(skillsDir, id)
if (!resolved.startsWith(`${skillsDir}/`)) {
if (!resolved.startsWith(`${skillsDir}${sep}`)) {
throw new Error('Invalid skill id')
}
return resolved
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27 changes: 27 additions & 0 deletions apps/server/tests/skills/service.test.ts
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Original file line number Diff line number Diff line change
@@ -0,0 +1,27 @@
import { describe, it } from 'bun:test'
import assert from 'node:assert'
import { sep } from 'node:path'

import { createSkillsRoutes } from '../../src/api/routes/skills'

describe('skills routes', () => {
const app = createSkillsRoutes()

it('GET /:id returns 404 for non-existent skill (not 500 from path check)', async () => {
const res = await app.request('/valid-skill-id')
assert.strictEqual(res.status, 404)
const body = await res.json()
assert.strictEqual(body.error, 'Skill not found')
})

it('GET /:id rejects path traversal attempts', async () => {
const res = await app.request('/../../../etc/passwd')
assert.notStrictEqual(res.status, 200)
})
Comment on lines +17 to +20
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@greptile-apps greptile-apps Bot Mar 12, 2026

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Path traversal test doesn't actually exercise the security check

The URL '/../../../etc/passwd' is normalized by the URL parser before Hono routes it. Per the URL standard, new URL('/../../../etc/passwd', 'http://localhost') resolves to http://localhost/etc/passwd, so :id becomes "etc/passwd" — not "../../../etc/passwd".

As a result, safeSkillDir("etc/passwd") resolves to ${skillsDir}/etc/passwd, which passes the traversal check (it's inside the skills dir). The test returns 404 only because no SKILL.md exists at that path, not because the security guard fired.

To actually exercise safeSkillDir's protection, test the service function directly or use percent-encoded dots that survive URL normalization:

import { safeSkillDir } from '../../src/skills/service'  // if exported, or test via internal module
// Or use percent-encoded traversal that bypasses URL normalization:
const res = await app.request('/..%2F..%2F..%2Fetc%2Fpasswd')
assert.notStrictEqual(res.status, 200)

Alternatively, if safeSkillDir is kept private, add a unit test that calls it directly with '../../../etc/passwd' and asserts it throws.

Prompt To Fix With AI 
This is a comment left during a code review.
Path: apps/server/tests/skills/service.test.ts
Line: 17-20

Comment:
**Path traversal test doesn't actually exercise the security check**

The URL `'/../../../etc/passwd'` is normalized by the URL parser before Hono routes it. Per the URL standard, `new URL('/../../../etc/passwd', 'http://localhost')` resolves to `http://localhost/etc/passwd`, so `:id` becomes `"etc/passwd"` — not `"../../../etc/passwd"`.

As a result, `safeSkillDir("etc/passwd")` resolves to `${skillsDir}/etc/passwd`, which **passes** the traversal check (it's inside the skills dir). The test returns 404 only because no `SKILL.md` exists at that path, not because the security guard fired.

To actually exercise `safeSkillDir`'s protection, test the service function directly or use percent-encoded dots that survive URL normalization:

```ts
import { safeSkillDir } from '../../src/skills/service'  // if exported, or test via internal module
// Or use percent-encoded traversal that bypasses URL normalization:
const res = await app.request('/..%2F..%2F..%2Fetc%2Fpasswd')
assert.notStrictEqual(res.status, 200)
```

Alternatively, if `safeSkillDir` is kept private, add a unit test that calls it directly with `'../../../etc/passwd'` and asserts it throws.

How can I resolve this? If you propose a fix, please make it concise.

})

describe('safeSkillDir uses platform separator', () => {
it(`path.sep is "${sep}" on this platform`, () => {
assert.ok(sep === '/' || sep === '\\')
})
})
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