Is CVE-2026-43634 in the CISA KEV catalog?

No. CVE-2026-43634 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-43634?

CVE-2026-43634 has a CVSS v3 base score of 7.5 (HIGH).

What is the EPSS score for CVE-2026-43634?

CVE-2026-43634 has an EPSS score of 0.24% (15th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate CVE-2026-43634?

No published fix for CVE-2026-43634 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

CVE & CISA-KEV Catalog

CVE-2026-43634

HIGH

7.5

CVSS v3

NVD

Description

HestiaCP versions 1.2.0 through 1.9.4 contain an IP spoofing vulnerability that allows unauthenticated remote attackers to bypass authentication security controls by supplying an arbitrary IP address in the CF-Connecting-IP HTTP header without verifying the request originated from Cloudflare's network. Attackers can exploit this to circumvent fail2ban brute-force protection, bypass per-user IP allowlists, and poison authentication audit logs by spoofing trusted IP addresses on each request.

CWE-348

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

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityHigh

AvailabilityNone

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

Exploit Intelligence

0.24%probability of exploitation in 30 days

15thpercentile

Low risk: more likely to be exploited than 15% of all known CVEs.

References

Other references5

Related Vulnerabilities

Other CWE-348 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2025-59951	Critical	9.1	4.7%	-	-
CVE-2022-31813	Critical	9.8	3.1%	-	Fix
CVE-2024-45410	Critical	9.8	1.5%	-	Fix
CVE-2021-21373	High	7.5	1.2%	-	Fix
CVE-2021-21374	High	8.1	1.0%	-	Fix
CVE-2022-2255	High	7.5	0.7%	-	Fix

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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 2026-07-14.