CVE-2026-33205Public exploit

Data exfiltration via arbitrary background-image requests

Published Mar 27, 2026 · Updated Mar 27, 2026

SSRF in calibre's e-book viewer web view before 9.6.0 allows context-dependent attackers to issue blind GET requests to arbitrary URLs. The background_image endpoint decodes an attacker-controlled filename and passes HTTP or HTTPS values directly to browser().open(), then returns and caches the response. A user must open attacker-controlled e-book content; the request can reach local-network services or carry sandboxed book data to an external server.

CVSS severity4.8
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

SSRF in calibre's e-book viewer web view before 9.6.0 allows context-dependent attackers to issue blind GET requests to arbitrary URLs. The background_image endpoint decodes an attacker-controlled filename and passes HTTP or HTTPS values directly to browser().open(), then returns and caches the response. A user must open attacker-controlled e-book content; the request can reach local-network services or carry sandboxed book data to an external server.

The record

CVE
CVE-2026-33205
Published
Mar 27, 2026
Updated
Mar 27, 2026
Vendor
Kovid Goyal
Product
calibre
Classifications
CWE-918, T1048
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 27, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=< 9.6.0

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

Kovid Goyal · calibreversion=< 9.6.0

Published CVSS scores

4.8GitHub, Inc.CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
5.5NIST NVDCVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-918Server-Side Request Forgery (SSRF)
T1048Exfiltration Over Alternative Protocol

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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