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MEDIUM severity

GHSA-m982-h4f8-g4hf — calibreweb

MEDIUMFix: janeczku/calibre-web@6f5390e

GHSA-m982-h4f8-g4hf is a medium-severity (CVSS 4.3) CWE-209 vulnerability in calibreweb. 1 public exploit reference exists, so weaponization risk is real. A fix is available for calibreweb — see the affected versions and patch details below.

Generation of Error Message Containing Sensitive Information in janeczku/calibre-web

Also known asCVE-2021-3986PYSEC-2026-1232
Published
Nov 15, 2024
Updated
Jul 7, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Sep 26, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.

Exploitation and automatability from CISA’s SSVC triage for GHSA-m982-h4f8-g4hf.

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs28th percentile — riskier than 28% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

GHSA-m982-h4f8-g4hf by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 379,842 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🐍calibreweb

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

A vulnerability in janeczku/calibre-web allows unauthorized users to view the names of private shelves belonging to other users. This issue occurs in the file shelf.py at line 221, where the name of the shelf is exposed in an error message when a user attempts to remove a book from a shelf they do not own. This vulnerability discloses private information and affects all versions prior to the fix.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIcalibreweball versions0.6.15pip install --upgrade 'calibreweb==0.6.15'

Affected Products

1 product · 1 configurations
Application
calibre-webjaneczku
< 0.6.15
range
Exploits & PoCs
1

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for calibreweb, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update calibreweb to 0.6.15 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-m982-h4f8-g4hf is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

A vulnerability in janeczku/calibre-web allows unauthorized users to view the names of private shelves belonging to other users. This issue occurs in the file shelf.py at line 221, where the name of the shelf is exposed in an error message when a user attempts to remove a book from a shelf they do not own. This vulnerability discloses private information and affects all versions prior to the fix.
O3 Security · Impact-Aware SCA

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