Is CVE-2026-27588 in the CISA KEV catalog?

No. CVE-2026-27588 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-27588?

CVE-2026-27588 has a CVSS v3 base score of 9.1 (CRITICAL).

What is the EPSS score for CVE-2026-27588?

CVE-2026-27588 has an EPSS score of 0.37% (29th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-27588?

Upgrade caddy on debian unstable to 2.11.2-1 or later.

CVE & CISA-KEV Catalog

CVE-2026-27588

CRITICAL

9.1

CVSS v3

NVD

Description

Caddy is an extensible server platform that uses TLS by default. Prior to version 2.11.1, Caddy's HTTP `host` request matcher is documented as case-insensitive, but when configured with a large host list (>100 entries) it becomes case-sensitive due to an optimized matching path. An attacker can bypass host-based routing and any access controls attached to that route by changing the casing of the `Host` header. Version 2.11.1 contains a fix for the issue.

CWE-178

How to fix

Remediation Available

caddyDebian

Fixed in:2.11.2-1CVE-2026-27588

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityNone

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

Exploit Intelligence

0.37%probability of exploitation in 30 days

29thpercentile

Low risk: more likely to be exploited than 29% of all known CVEs.

References

Exploit1

github.com

Release Notes1

github.com

Related Vulnerabilities

Other CWE-178 vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2025-27636	Medium	5.6	80%	-	Fix
CVE-2021-24347	High	8.8	52%	-	Fix
CVE-2020-12812	Critical	9.8	49%	KEV + Ransom	Fix
CVE-2003-0411	High	7.5	25%	-	-
CVE-2018-9845	Critical	9.8	13%	-	Fix
CVE-2001-0766	Critical	9.8	8.2%	-	-

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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 2026-02-25.