Is CVE-2026-46431 in the CISA KEV catalog?

No. CVE-2026-46431 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-46431?

CVE-2026-46431 has a CVSS v3 base score of 4.3 (MEDIUM).

What is the EPSS score for CVE-2026-46431?

CVE-2026-46431 has an EPSS score of 0.22% (12th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate 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.

CVE & CISA-KEV Catalog

CVE-2026-46431

MEDIUM

4.3

CVSS v3

NVD

Description

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.

CWE-942

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.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionRequired

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityNone

AvailabilityNone

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

Exploit Intelligence

0.22%probability of exploitation in 30 days

12thpercentile

Low risk: more likely to be exploited than 12% of all known CVEs.

References

Other references1

github.com

Embed a live status badge for CVE-2026-46431

Markdown

[![CVE-2026-46431](https://tridentstack.com/cve/badge/CVE-2026-46431.svg)](https://tridentstack.com/cve/CVE-2026-46431)

HTML

<a href="https://tridentstack.com/cve/CVE-2026-46431"><img src="https://tridentstack.com/cve/badge/CVE-2026-46431.svg" alt="CVE-2026-46431"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

Start free

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 2026-05-26.