CVE-2026-52845 Details
Caddy is an extensible server platform that uses TLS by default. Prior to 2.11.4, forward_auth copy_headers deletes the exact client-supplied identity header before copying the trusted value from the auth gateway. But when the request later goes through php_fastcgi, Caddy normalizes HTTP headers into CGI variables by replacing - with _. This lets a client send an underscore alias that survives the forward_auth delete step but becomes the same PHP/FastCGI variable. Result: a remote client can inject or sometimes override identity/group headers trusted by PHP/FastCGI applications behind Caddy. This vulnerability is fixed in 2.11.4.
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Exploit prediction scoring system (EPSS) score for CVE-2026-52845
EPSS (Exploit Prediction Scoring System): EPSS predicts the likelihood that a vulnerability will be exploited in the wild. A higher percentage means a greater chance of an exploit occurring. The EPSS model produces a probability score between 0 and 1 (0 and 100%).
0.25 Probability of exploitation activity being observed over the next 30 days (16th percentile)
CVSS score for CVE-2026-52845
CVSS (Common Vulnerability Scoring System): An open framework owned and managed by FIRST.Org, Inc. that assigns a numerical score from 0 to 10 to software vulnerabilities to indicate their severity.
8.1 High
Products affected by CVE-2026-52845
Caddy 0.11.1
Caddy 2.7.6
Caddy 2.4.6
Caddy 2.8.4
Caddy 2.7.5
DVE Score by Bitsight AI
DVE scores complement traditional static scoring systems like CVSS with Bitsight AI powered real-time threat intelligence and underground cyber criminal activity so that security teams can reduce alert fatigue and focus on vulnerabilities most likely to be exploited.
Low
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CVE-2026-52845 Global Footprint

Top 10 Identified Countries

Country Observations Percentage
PL 238 35.90%
CN 159 23.98%
US 58 8.75%
HU 35 5.28%
SG 33 4.98%
SK 31 4.68%
DE 25 3.77%
BG 17 2.56%
IT 12 1.81%
GB 11 1.66%

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CVE-2026-52845 Industry Footprint

Top 10 Identified Industries

*Service provider organizations (typically Technology and Telecommunications) are disproportionally represented in the results given their upstream ownership of end-user infrastructure. See our FAQs.

Industry* Observations Percentage
Technology 261 86.71%
Telecommunications 40 13.29%

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