CVE-2020-23356Network attack vector

Unauthenticated login bypass via loose hash comparison

Published Jan 27, 2021 · Updated Aug 4, 2024

Authentication bypass in Nibbleblog 3.7.1c allows remote attackers to authenticate through the admin login with a crafted password. In admin/kernel/api/login.class.php, verify_login hashes the supplied password with SHA-1 and loosely compares the result to the stored hash, so numeric-looking 0e hashes coerce to zero. Exploitation requires the stored hash and attacker-generated hash to use PHP's numeric 0e form; success creates an authenticated administrative session.

CVSS severity7.5
High
EPSS probability0.98%
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 Nibbleblog 3.7.1c allows remote attackers to authenticate through the admin login with a crafted password. In admin/kernel/api/login.class.php, verify_login hashes the supplied password with SHA-1 and loosely compares the result to the stored hash, so numeric-looking 0e hashes coerce to zero. Exploitation requires the stored hash and attacker-generated hash to use PHP's numeric 0e form; success creates an authenticated administrative session.

The record

CVE
CVE-2020-23356
Published
Jan 27, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jan 27, 2021CVE 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 NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:P/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 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

T1190Exploit Public-Facing Application

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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