CVE-2026-46431

Algernon is a small self-contained pure-Go web server. Prior to 1.17.7, the SSE event server's Access-Control-Allow-Origin response header was hardcoded to the wildcard * regardless of the caller's Origin. Because EventSource does not preflight and does not send cookies, the wildcard is sufficient to let any third-party page the developer visits open a cross-origin EventSource to the SSE port and read the live filename stream from JavaScript. This vulnerability is fixed in 1.17.7.

CVSS v3 4.3 MEDIUM

4.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 2.8 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction REQUIRED

Confidentiality Impact LOW

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://github.com/xyproto/algernon/security/advisories/GHSA-hw27-4v2q-5qff
https://github.com/xyproto/algernon/security/advisories/GHSA-hw27-4v2q-5qff

Configurations

No configuration.

History

No history.

Information

Published : 2026-05-26 17:16

Updated : 2026-07-24 11:10

NVD link : CVE-2026-46431

Mitre link : CVE-2026-46431

CVE.ORG link : CVE-2026-46431

JSON object : View

Products Affected

No product.

CWE

CWE-942

Permissive Cross-domain Security Policy with Untrusted Domains

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