Is CVE-2026-27588 actively exploited?

A proof-of-concept exploit is publicly available for CVE-2026-27588, but active exploitation has not been confirmed.

Can CVE-2026-27588 be exploited remotely?

Yes. CVE-2026-27588 is exploitable remotely over the network (CVSS attack vector: Network).

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

CVE-2026-27588 has a CVSS score of 9.1 (CRITICAL) and an EPSS exploitation probability of 0.03%.

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CRITICALPOC

CVE-2026-27588

CWE-178Published: February 24, 2026· Updated: Feb 25, 2026

9.1

CVSS v3.1

EPSS:0.03%probability of exploitation in 30 daysPercentile:8.6th

Official 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.

NVD Source

Risk Analysis

This critical vulnerability in Caddy allows attackers to bypass host-based routing and access controls. The flaw occurs when Caddy's HTTP host matcher, intended to be case-insensitive, becomes case-sensitive with large host lists. A high CVSS score of 9.1 indicates severe impact, but a low EPSS score suggests a very low probability of exploitation.

A proof-of-concept exploit has been published, indicating that the vulnerability is understood and can be demonstrated. It is remotely exploitable due to the network attack vector and low attack complexity.

Recommended Action

Administrators should upgrade Caddy to version 2.11.1 or later to fix this issue. Ensure all host-based routing and access control configurations are reviewed after the update.

Generated by the CTIWATCH analysis pipeline from this CVE's metadata (CVSS, EPSS, KEV status, exploit intelligence). Verify against vendor advisories before acting.

Technical Analysis

CVE-2026-27588 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

A successful exploit results in complete confidentiality breach (data exposure), full integrity compromise (data manipulation), with a CVSS base score of 9.1.

A proof-of-concept (PoC) exploit exists for CVE-2026-27588. While not yet confirmed in active campaigns, the availability of PoC code increases exploitation risk substantially.