Is CVE-2026-48126 in the CISA KEV catalog?

No. CVE-2026-48126 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-48126?

CVE-2026-48126 has a CVSS v3 base score of 8.2 (HIGH).

What is the EPSS score for CVE-2026-48126?

CVE-2026-48126 has an EPSS score of 0.34% (25th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2026-48126

HIGH

8.2

CVSS v3

NVD

Description

Algernon is a small self-contained pure-Go web server. Prior to 1.17.8, when algernon is started with --domain (or --letsencrypt, which silently turns on --domain at engine/flags.go:372), the request handler resolves the served directory by joining the configured --dir with the value of the client-supplied Host header. The join is performed by filepath.Join with no validation, so a Host: .. header walks one level above the document root. Subsequent file resolution then exposes everything in that parent directory — arbitrary file read, full directory listing, and, if any .lua file is present, server-side Lua execution. This vulnerability is fixed in 1.17.8.

CWE-22Path Traversal CWE-23 CWE-644

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityLow

AvailabilityNone

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

Exploit Intelligence

0.34%probability of exploitation in 30 days

25thpercentile

Low risk: more likely to be exploited than 25% of all known CVEs.

References

https://github.com/xyproto/algernon/security/advisories/GHSA-jc3j-x6pg-4hmv

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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 2026-05-26.