CVE-2026-24664Network attack vector

Account enumeration via inconsistent session cookie issuance

Published Feb 3, 2026 · Updated Feb 3, 2026

Username enumeration in Open eClass before 4.2 allows remote attackers to identify valid accounts through unauthenticated login requests. The login endpoint sets a PHPSESSID cookie for a valid username but omits it for an invalid one, exposing account existence through the Set-Cookie header. No credentials or user interaction are required; the disclosure is limited to valid usernames and supports automated account-list building.

CVSS severity5.3
Medium
EPSS probability0.26%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Username enumeration in Open eClass before 4.2 allows remote attackers to identify valid accounts through unauthenticated login requests. The login endpoint sets a PHPSESSID cookie for a valid username but omits it for an invalid one, exposing account existence through the Set-Cookie header. No credentials or user interaction are required; the disclosure is limited to valid usernames and supports automated account-list building.

The record

CVE
CVE-2026-24664
Published
Feb 3, 2026
Updated
Feb 3, 2026
Vendor
Greek Universities Network
Product
Open eClass
Classifications
CWE-204
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 3, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 3, 2026Record 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=< 4.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Greek Universities Network · Open eClassversion=< 4.2

Published CVSS scores

5.3GitHub, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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

CWE-204Observable Response Discrepancy

Public exploit references

No public exploit references are available in this record.

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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