CVE-2026-46431
MEDIUMDescription
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.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:N
Exploit Intelligence
Low risk: more likely to be exploited than 12% of all known CVEs.
References
Related Vulnerabilities
Other CWE-942 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2026-22812 | High | 8.8 | 17% | - | Fix |
| CVE-2023-38122 | High | 7.2 | 1.9% | - | Fix |
| CVE-2019-14860 | Medium | 6.5 | 1.2% | - | Fix |
| CVE-2023-38125 | High | 8.8 | 1.1% | - | Fix |
| CVE-2022-31736 | Critical | 9.8 | 1.1% | - | Fix |
| CVE-2020-36851 | Unscored | - | 1.0% | - | - |
Common questions
How do I fix CVE-2026-46431?
No published fix for CVE-2026-46431 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-46431 being actively exploited?
Not that we know of. CVE-2026-46431 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.22% is the estimated probability that it will be exploited in the next 30 days. That is higher than 12% of all scored CVEs.
How severe is CVE-2026-46431?
CVE-2026-46431 has a CVSS v3 base score of 4.3, rated medium. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-24.