Path Traversal in wisp.serve_static allows arbitrary file read
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- Information disclosure
- Confidentiality · integrity · availability
- High · None · None
- Fix status
- Fixed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and GitHub. Impact type from CWE-22 and the CVSS impact.
Summary
Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in gleam-wisp wisp allows arbitrary file read via percent-encoded path traversal. The wisp.serve_static function is vulnerable to path traversal because sanitization runs before percent-decoding. The encoded sequence %2e%2e passes through string.replace unchanged, then uri.percent_decode converts it to .., which the OS resolves as directory traversal when the file is read. An unauthenticated attacker can read any file readable by the application process in a single HTTP request, including application source code, configuration files, secrets, and system files. This issue affects wisp: from 2.1.1 before 2.2.1.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| gleam-wisp | wisp | 2.1.1 to before 2.2.1 | 2.2.1 | Patch available | CNA |
| — | wisp (Hex) | 2.1.1 to before 2.2.1 | 2.2.1 | Patch available | GHSA-h7cj-j2vv-qw8r |
- wisp Vendorgleam-wisp Affected 2.1.1 to before 2.2.1 Fixed in 2.2.1 Patch available CNA
- wisp (Hex) Vendor— Affected 2.1.1 to before 2.2.1 Fixed in 2.2.1 Patch available GHSA-h7cj-j2vv-qw8r
CPE configurations NVD · 1
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:gleam-wisp:wisp:*:*:*:*:*:*:*:* | 2.1.1 to before 2.2.1 | Vulnerable | gleam-wisp |
- cpe:2.3:a:gleam-wisp:wisp:*:*:*:*:*:*:*:* Versions 2.1.1 to before 2.2.1 Vulnerable ·gleam-wisp
Remediation
- Fix · CNA wisp (gleam-wisp) Fixed in 2.2.1
- Fix · GHSA-h7cj-j2vv-qw8r wisp (Hex) Fixed in 2.2.1 Advisory →
Timeline
- 2026-10-02 Threatist record created from CVE-2026-28807
- 2026-10-03 Alias added: GHSA-h7cj-j2vv-qw8r
References
Advisory 3
More gleam-wisp Wisp vulnerabilities
- TI-2026-24682 Multipart form body parser bypasses body size limits in wisp CVSS 4.0HIGH 8.7
Sources
- CVE-2026-28807 · CVE Program
- CVE-2026-28807 · NVD
- FIRST EPSS
- GHSA-h7cj-j2vv-qw8r · GitHub Advisory Database · CC BY 4.0
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