Punk for Perl skips Origin check on WebSocket handshakes
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- Low · None · None
- Fix status
- Fixed
Attack profile from CVSS 3.1 · CISA ADP. Fix status from CNA.
Summary
Punk versions from 0.48 before 0.55 for Perl route HTTP/2 and HTTP/3 Extended CONNECT requests, which are used for WebSocket handshakes, to any GET route without checking the Origin header (CWE-1385). Because the Origin check runs only when a WebSocket route matches, a cross-origin web page can open a WebSocket to any path. The page can then learn from the open or error event whether that path returns a 2xx status.
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
Description from the CNA
Punk versions from 0.48 before 0.55 for Perl route Extended CONNECT requests to any GET route without an Origin check in ps_serve_one. On HTTP/2 and HTTP/3 a WebSocket handshake arrives as an Extended CONNECT, which is matched as a GET and so reaches every GET route, API operation and mount. The Origin check runs only when a websocket route matches. On this transport the handler's status is the handshake response, and a 2xx accepts it. A cross-origin page can open a WebSocket to any path and learn from its open or error event whether that path returns 2xx.
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 |
|---|---|---|---|---|---|
| — | Punk | 0.48 to before 0.55 | 0.55 | Patch available | CNA |
- Punk Vendor— Affected 0.48 to before 0.55 Fixed in 0.55 Patch available CNA
Remediation
Punk 0.55 fixes this flaw, so upgrade Punk for Perl to 0.55 or later.
Written with Claude Haiku 5.5 from the sources below · 2026-10-29
- Fix · CNA Punk Fixed in 0.55
Timeline
- 2026-10-06 Threatist record created from CVE-2026-104380
- 2026-10-06 Alias added: GHSA-cmh9-2wr3-4x64
- 2026-10-06 CVSS score added · CISA ADP
- 2026-10-06 CISA SSVC decision points changed
References
Sources
- CVE-2026-104380 · CVE Program
- CVE-2026-104380 · NVD
- FIRST EPSS
- GHSA-cmh9-2wr3-4x64 · GitHub Advisory Database · CC BY 4.0
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