CVE-2020-35591Public exploitNetwork attack vector

Account hijacking via unreplaced pre-authentication session identifier

Published Feb 18, 2021 · Updated Aug 4, 2024

Session fixation in the Pi-hole web interface 5.0, 5.1, and 5.1.1 allows remote attackers to hijack accounts via PHPSESSID. The login endpoint accepts a PHPSESSID cookie chosen before authentication and retains that identifier after a victim signs in. Exploitation requires user interaction to place the chosen cookie in an authenticated victim's browser; reuse of the identifier grants access to that active account session.

CVSS severity5.4
Medium
EPSS probability1.14%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Session fixation in the Pi-hole web interface 5.0, 5.1, and 5.1.1 allows remote attackers to hijack accounts via PHPSESSID. The login endpoint accepts a PHPSESSID cookie chosen before authentication and retains that identifier after a victim signs in. Exploitation requires user interaction to place the chosen cookie in an authenticated victim's browser; reuse of the identifier grants access to that active account session.

The record

CVE
CVE-2020-35591
Published
Feb 18, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-384, T1539
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 18, 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

5.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-384Session Fixation
T1539Steal Web Session Cookie

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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