CVE-2023-4649Public exploitNetwork attack vector

Session hijacking via unrotated login identifier

Published Aug 31, 2023 · Updated Oct 1, 2024

Session fixation in InstantCMS 2 before 2.16.1 allows remote authenticated users to reuse a fixed session identifier after login. The loginComplete and autoLogin paths retain the preauthentication PHP session identifier instead of regenerating it when authentication succeeds. Remote authenticated users must first establish or control that identifier, then can reuse the victim's authenticated session to read session-bound information.

CVSS severity4.3
Medium
EPSS probability0.44%
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 InstantCMS 2 before 2.16.1 allows remote authenticated users to reuse a fixed session identifier after login. The loginComplete and autoLogin paths retain the preauthentication PHP session identifier instead of regenerating it when authentication succeeds. Remote authenticated users must first establish or control that identifier, then can reuse the victim's authenticated session to read session-bound information.

The record

CVE
CVE-2023-4649
Published
Aug 31, 2023
Updated
Oct 1, 2024
Vendor
InstantCMS Team
Product
InstantCMS 2
Classifications
CWE-384, T1539
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 31, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 1, 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?

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

  1. Affected versionversion=unspecified <2.16.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

InstantCMS Team · InstantCMS 2version=unspecified <2.16.1

Published CVSS scores

4.3huntr.devCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
5.4NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/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
Privilegesauthenticated
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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