CVE-2026-104380 (CVSS 5.3)

Description

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.

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CVSS v3.1 Score

5.3

MEDIUM

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

EPSS — Exploit Prediction

0.0016

Probability of exploitation

0.05%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-1385 CWE-1385

References

Other References

https://metacpan.org/release/LNATION/Punk-0.55/changes https://metacpan.org/release/LNATION/Punk-0.55/diff/LNATION/Punk-0.54 http://www.openwall.com/lists/oss-security/2026/10/06/1

Frequently Asked Questions

What is CVE-2026-104380? +

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. It has a CVSS v3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-104380? +

CVE-2026-104380 has a CVSS v3.1 score of 5.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0016, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-104380? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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