CVE-2020-12627Network attack vector

Authentication bypass via forgeable session cookies

Published May 4, 2020 · Updated Aug 4, 2024

Authentication bypass in Calibre-Web 0.6.6 allows remote attackers to impersonate users by forging Flask session cookies. The create_app function in cps/init.py assigns a fixed fallback app.secret_key, so default instances accept cookies signed with the same public value. No credentials or user interaction are required; a forged cookie grants the authorization state encoded in the selected session.

CVSS severity9.8
Critical
EPSS probability1.37%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Calibre-Web 0.6.6 allows remote attackers to impersonate users by forging Flask session cookies. The create_app function in cps/init.py assigns a fixed fallback app.secret_key, so default instances accept cookies signed with the same public value. No credentials or user interaction are required; a forged cookie grants the authorization state encoded in the selected session.

The record

CVE
CVE-2020-12627
Published
May 4, 2020
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-798, T1550.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 4, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

7.5NIST NVDAV:N/AC:L/Au:N/C:P/I:P/A:P
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-798Use of Hard-coded Credentials
T1550.004Use Alternate Authentication Material: Web Session Cookie

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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