Kestrel: Out-of-bounds Read
CVE-2026-42799 is a critical-severity out-of-bounds read vulnerability in Kestrel from ASR, 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 2026/02/10 as the first without the flaw, so updating Kestrel to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.28% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Kestrel to 2026/02/10 or a later version.
- Update Asr1803 Firmware to 1.216.002 or a later version.
- Read the advisory on asrmicro.com 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
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| ASR | Kestrel | before 2026/02/10 | 2026/02/10 |
| Asrmicro | Asr1803 Firmware | before 1.216.002 | 1.216.002 |
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 NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.4 | High | CNA |
| CVSS 3.1 | 9.8 | Critical | NVD |
Official description
Out-of-bounds read vulnerability in ASR Kestrel (nr_fw modules) allows Overflow Buffers. This vulnerability is associated with program files Code/Nr/nr_fw/RA/src/NrPwrCtrl.C. This issue affects Kestrel: before 2026/02/10.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Read
The product reads data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that provides appropriate memory abstractions.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: partial).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Recent Out-of-bounds Read vulnerabilities
- 7.8 High severity
- 8.8 High severity
- 9.1 Critical severity
- 8.2 High severity
- 7.5 High severity
- 7.5 High severity
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