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VulnerabilityPublished

CVE-2026-33205: kovidgoyal calibre · Server-Side Request Forgery (SSRF)

Affects kovidgoyal calibreSource CVE Database V5

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Not known to be exploited · CVSS 4.8 Medium : upgrade to 9.6.0 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score
4.8Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 9.6.0
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

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 Mar 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade calibre and kovidgoyal/calibre to 9.6.0.

Affected software

ProductAffectedFixed in
kovidgoyalcalibreAffected
  • <9.6.0
Fixed in
  • 9.6.0
GitHubkovidgoyal/calibrepkg:github/kovidgoyal/calibreOther threatsAffected
  • <9.6.0
Fixed in
  • 9.6.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

To mitigate CVE-2026-33205, organizations and users should upgrade calibre to version 9.6.0 or later, where the vulnerability is patched. Until upgrading is possible, users should avoid opening untrusted or suspicious e-books that could trigger the SSRF. Network-level mitigations include restricting outbound HTTP requests from the host running calibre to only trusted destinations, using firewall rules or proxy controls to limit arbitrary URL access. Additionally, sandboxing calibre execution environments or running it with least privilege can reduce the impact of exploitation. Monitoring network traffic for unusual outbound requests originating from calibre may help detect exploitation attempts. Developers and administrators should review and harden any web view components or background image handling features in similar applications to prevent SSRF vulnerabilities. Regularly applying security updates and educating users about the risks of opening untrusted content are essential complementary measures.

Description

calibre is a cross-platform e-book manager for viewing, converting, editing, and cataloging e-books. Prior to version 9.6.0, a Server-Side Request Forgery vulnerability in the background-image endpoint of calibre e-book reader's web view allows an attacker to perform blind GET requests to arbitrary URLs and exfiltrate information out from the ebook sandbox. Version 9.6.0 patches the issue.

References

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