CVE-2026-93955Public exploitNetwork attack vectorHinoki check available

Authenticated book disclosure via unchecked bookId

Published Sep 19, 2026 · Updated Sep 19, 2026

Authorization bypass in Grimmory 3.3.0 through 3.4.1 allows remote authenticated users to download books from unassigned libraries via bookId. The Kobo download path passes the requested book to streamFileToResponse, which opens and streams its EPUB or CBX file without validateBookContentAccess. Exploitation requires syncKobo permission, a valid Kobo token, limited library assignments, and the numeric ID of a book in another library.

CVSS severityUnavailable
Unscored
EPSS probability0.41%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Authorization bypass in Grimmory 3.3.0 through 3.4.1 allows remote authenticated users to download books from unassigned libraries via bookId. The Kobo download path passes the requested book to streamFileToResponse, which opens and streams its EPUB or CBX file without validateBookContentAccess. Exploitation requires syncKobo permission, a valid Kobo token, limited library assignments, and the numeric ID of a book in another library.

The record

CVE
CVE-2026-93955
Published
Sep 19, 2026
Updated
Sep 19, 2026
Vendor
Grimmory
Product
Grimmory
Classifications
CWE-639, T1213
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 19, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=3.3.0
  2. Affected versionversion=3.3.1
  3. Affected versionversion=3.3.2
  4. Affected versionversion=3.3.3
  5. Affected versionversion=3.4.0
  6. Affected versionversion=3.4.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Grimmory · Grimmoryversion=3.3.0; version=3.3.1; version=3.3.2; version=3.3.3; version=3.4.0; version=3.4.1

Published CVSS scores

5.3OffSeqCVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N/E:P

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.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-639Authorization Bypass Through User-Controlled Key
T1213Data from Information Repositories

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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