CVE-2026-27810 Details
calibre is a cross-platform e-book manager for viewing, converting, editing, and cataloging e-books. Prior to version 9.4.0, an HTTP Response Header Injection vulnerability in the calibre Content Server allows any authenticated user to inject arbitrary HTTP headers into server responses via an unsanitized `content_disposition` query parameter in the `/get/` and `/data-files/get/` endpoints. All users running the calibre Content Server with authentication enabled are affected. The vulnerability is exploitable by any authenticated user and can also be triggered by tricking an authenticated victim into clicking a crafted link. Version 9.4.0 contains a fix for the issue.
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Exploit prediction scoring system (EPSS) score for CVE-2026-27810
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%).
0.21 Probability of exploitation activity being observed over the next 30 days (11th percentile)
CVSS score for CVE-2026-27810
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.
6.4 Medium
Products affected by CVE-2026-27810
Calibre 1.48.0
Calibre 2.83.0
Calibre 3.39.1
Calibre 3.48.0
Calibre 4.15.0
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-2026-27810 Global Footprint

Top 10 Identified Countries

Country Observations Percentage
US 303 35.77%
CN 165 19.48%
SG 86 10.15%
DE 63 7.44%
GB 48 5.67%
JP 24 2.83%
ID 14 1.65%
ES 14 1.65%
PH 10 1.18%
CA 10 1.18%

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CVE-2026-27810 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 503 87.63%
Telecommunications 66 11.50%
Education 2 0.35%
Government/Politics 1 0.17%
Utilities 1 0.17%
Business Services 1 0.17%

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