CVE-2026-24664VulnerabilityPublished 3 Feb 2026

CVE-2026-24664: gunet openeclass · Observable Response Discrepancy

Affects gunet openeclassSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium : upgrade to 4.2 when convenient.

Data as of 26 Oct 2026, 08:30 UTC

CVSS 3.1 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.2% chance of exploitation in 30 days – higher than 21% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 4.2

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: None
Availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 3 Feb 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade openeclass and gunet/openeclass to 4.2.

Affected software

Product	Affected	Fixed in
gunetopeneclass	Affected <4.2	Fixed in 4.2
GitHubgunet/openeclass`pkg:github/gunet/openeclass`Other threats	Affected <4.2	Fixed in 4.2

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

The primary and most effective mitigation is to upgrade Open eClass to version 4.2 or later, where the username enumeration vulnerability has been patched by normalizing login response behaviors. Organizations should audit their current Open eClass installations to identify affected versions and prioritize updates. In addition to patching, administrators can implement monitoring and alerting on login endpoints to detect unusual patterns indicative of enumeration attempts, such as rapid login failures or repeated requests with varying usernames from single IP addresses. Rate limiting and IP blacklisting can further reduce the risk of automated enumeration. Employing multi-factor authentication (MFA) can mitigate the impact of username disclosure by adding an additional layer of security. User education on phishing risks and secure password practices should complement technical controls. Finally, reviewing and minimizing information leakage in error messages and response times across all authentication interfaces is recommended to prevent similar enumeration issues.

Description

CVE-2026-24664 is a medium severity username enumeration vulnerability in the Open eClass platform (formerly GUnet eClass) versions prior to 4.2. It allows unauthenticated attackers to identify valid usernames by analyzing observable differences in login response behavior. This vulnerability does not impact confidentiality beyond username disclosure, nor does it affect integrity or availability. Exploitation requires no authentication or user interaction and can be performed remotely over the network. The issue has been patched in version 4.2. European organizations using affected versions should update promptly to prevent potential reconnaissance activities that could facilitate further attacks. Countries with significant adoption of Open eClass in educational institutions are most at risk. Mitigation involves upgrading to version 4.

Impact

For European organizations, particularly educational institutions using Open eClass versions prior to 4.2, this vulnerability enables attackers to enumerate valid usernames remotely without authentication. This can lead to increased risk of targeted attacks such as credential stuffing, brute force password attempts, or social engineering campaigns against identified users. While the vulnerability does not directly compromise sensitive data or system integrity, the exposure of valid usernames undermines user privacy and can serve as a stepping stone for more severe attacks. The impact is heightened in environments where usernames correspond to real identities of students, faculty, or staff, potentially exposing them to phishing or identity theft. Additionally, enumeration can facilitate automated attacks that degrade system availability indirectly. Given the widespread use of Open eClass in European academic institutions, the vulnerability could affect a significant user base if unpatched. However, the lack of known active exploitation reduces immediate risk, though the medium severity rating warrants prompt remediation.

Summary

CVE-2026-24664 identifies a username enumeration vulnerability in the Open eClass platform, a comprehensive course management system widely used in academic environments. The vulnerability arises from observable response discrepancies during the login process in versions prior to 4.2. Specifically, when an attacker submits a login request with a username, the system's response behavior differs depending on whether the username exists or not. These differences can be timing variations, error messages, or other subtle response characteristics that allow an unauthenticated attacker to confirm valid usernames without needing credentials or user interaction. This type of vulnerability falls under CWE-204: Observable Response Discrepancy. Although it does not directly expose passwords or sensitive data, username enumeration is a critical reconnaissance step that can facilitate targeted brute force or phishing attacks. The vulnerability has a CVSS v3.1 base score of 5.3 (medium severity), reflecting its network attack vector, low attack complexity, no privileges required, and no user interaction needed. The issue was publicly disclosed in early 2026 and has been addressed in Open eClass version 4.2, which standardizes login responses to prevent enumeration. No known exploits are currently reported in the wild, but the vulnerability's presence in educational platforms makes it a notable risk for institutions relying on Open eClass for course management.

CWE-204Observable Response Discrepancy (opens in a new tab)
Base weakness
The product provides different responses to incoming requests in a way that reveals internal state information to an unauthorized actor outside of the intended control sphere.
Architecture and Design · Separation of Privilege
Compartmentalize the system to have "safe" areas where trust boundaries can be unambiguously drawn. Do not allow sensitive data to go outside of the trust boundary and always be careful when interfacing with a compartment outside of the safe area.
Implementation
Ensure that error messages only contain minimal details that are useful to the intended audience and no one else. The messages need to strike the balance between being too cryptic (which can confuse users) or being too detailed (which may reveal more than intended).
OWASP Cheat Sheets
Error Handling (opens in a new tab)
Logging (opens in a new tab)
OWASP ASVS 4.0.3
V8.3.4 (opens in a new tab)
V14.3.3 (opens in a new tab)
V7.3.3 (opens in a new tab)
Attack patterns
ICMP IP Total Length Field Probe (opens in a new tab)
ICMP IP 'ID' Field Error Message Probe (opens in a new tab)
Application Fingerprinting (opens in a new tab)
System Footprinting (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

github.com/gunet/openeclass/security/advisories/GHSA-c3wq-m629-5h2j (opens in a new tab)

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 11 Feb 2026, 11:55 UTC

WeaknessesCWE-204

Technical details

References

Community reviews

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