Nedi: Observable Discrepancy
CVE-2022-40895 is a critical-severity observable discrepancy vulnerability in Nedi, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Nedi versions: 1.0.7 and earlier; 1.0.7. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 2.07% chance of exploitation within 30 days, higher than 82% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of Nedi you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on forum.nedi.ch for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
Version data comes from NVD's product matching. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. Scored by NVD.
Official description
In certain Nedi products, a vulnerability in the web UI of NeDi login & Community login could allow an unauthenticated, remote attacker to affect the integrity of a device via a User Enumeration vulnerability. The vulnerability is due to insecure design, where a difference in forgot password utility could allow an attacker to determine if the user is valid or not, enabling a brute force attack with valid users. This affects NeDi 1.0.7 for OS X 1.0.7 <= and NeDi for Suse 1.0.7 <= and NeDi for FreeBSD 1.0.7 <=.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Observable Discrepancy
The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.
How developers prevent this class of flaw
- 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. Ensure that appropriate compartmentalization is built into the system design, and the compartmentalization allows for and reinforces privilege separation functionality. Architects and designers should rely on the principle of least privilege to decide the appropriate time to use privileges and the time to drop privileges.
Timeline
- CVE record published.
- Record last changed materially (score, affected products, status or references).
References
Advisories
Technical write-ups (may include proof of concept)
- gist.github.com/UditChavda/2f2effa477a429b485ae7e2dc3bbd04fExploit, Third Party Advisory
Recent Observable Discrepancy vulnerabilities
- 7.8 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 7.5 High severity
- 9.8 Critical severity
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