RouterOS: Integer Underflow (Wrap or Wraparound)
CVE-2026-84411 is a critical-severity integer underflow (wrap or wraparound) vulnerability in RouterOS from MikroTik, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 7.24 as the first without the flaw, so updating RouterOS to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.86% chance of exploitation within 30 days, higher than 59% of scored CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update RouterOS to 7.24 or a later version.
- 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 the organisation that assigned the CVE. 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
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by CNA (hq.dhs.gov).
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 9.3 | Critical | CNA (hq.dhs.gov) |
| CVSS 3.1 | 9.8 | Critical | CNA (hq.dhs.gov) |
Official description
The web management service in affected RouterOS versions contains an integer underflow in its HTTP request body handling that is reachable before authentication. This can be leveraged by an unauthenticated network attacker to achieve arbitrary code execution as root, or to cause a denial of service, using a single crafted request.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Integer Underflow (Wrap or Wraparound)
The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.
More Integer Underflow (Wrap or Wraparound) vulnerabilities (CWE-191)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Other references
Other vulnerabilities in RouterOS
- 7.4 High severity
- 8.8 High severity
- 7.5 High severity
- 7.5 High severity
- 8.8 High severity
- 9.8 Critical severity
Recent Integer Underflow (Wrap or Wraparound) vulnerabilities
- 8.7 High severity
- 8.2 High severity
- 7.8 High severity
- 7.8 High severity
- 7.5 High severity
- 7.5 High severity
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