Description
In OpenBSD through 7.8, the slaacd and rad daemons have an infinite loop when they receive a crafted ICMPv6 Neighbor Discovery (ND) option (over a local network) with length zero, because of an "nd_opt_len * 8 - 2" expression with no preceding check for whether nd_opt_len is zero.
Published: 2026-04-20
Score: 4.3 Medium
EPSS: < 1% Very Low
KEV: No
Impact: Denial of Service
Action: Apply Patch
AI Analysis

Impact

The slaacd and rad daemons in OpenBSD versions up through 7.8 process crafted ICMPv6 Neighbor Discovery options. If an option of length zero is received, the unvalidated calculation of nd_opt_len * 8 - 2 causes the parsing loop to never terminate, resulting in an infinite loop that stalls the daemon. The flaw is a classic example of unchecked input leading to an unbounded loop, classified as CWE‑1284 and CWE‑835.

Affected Systems

This flaw affects the OpenBSD operating system, specifically the SLAACD and RAD network daemons in releases up to 7.8. Network hosts running these daemons are vulnerable. No specific hardware vendors are listed; all OpenBSD installations in this version range are potentially impacted.

Risk and Exploitability

The vulnerability does not carry an inherent network‑wide lateral movement requirement; an attacker only needs local or lateral network access to send a crafted packet to the target host. Because the flaw leads to a denial of service of the affected daemons, any system relying on SLAACD or RAD for address configuration can experience network disruption. The EPSS score is < 1% and the flaw is not listed in KEV, indicating limited known exploitation at this time. Nevertheless, the lack of mitigations beyond the infinite loop makes patching essential.

Generated by OpenCVE AI on April 28, 2026 at 16:20 UTC.

Remediation

No vendor fix or workaround currently provided.

OpenCVE Recommended Actions

  • Update your system to OpenBSD 7.9 or later, where the patch is integrated.
  • Apply the cherry‑pick commit 086c5738bcd3c203bcc08d024fcf983cb409115f manually to your source tree and rebuild the daemons if you cannot jump to a newer release.
  • Restart slaacd and rad to ensure the updated binaries are in use.
  • As a temporary measure, configure local firewall rules to drop malformed ICMPv6 ND options that have a length field of zero.

Generated by OpenCVE AI on April 28, 2026 at 16:20 UTC.

Tracking

Sign in to view the affected projects.

Advisories

No advisories yet.

History

Tue, 28 Apr 2026 16:45:00 +0000

Type Values Removed Values Added
Title Infinite Loop in OpenBSD SLAACD and RAD Daemons Due to Zero-Length ICMPv6 ND Option

Fri, 24 Apr 2026 19:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-835
CPEs cpe:2.3:o:openbsd:openbsd:*:*:*:*:*:*:*:*

Wed, 22 Apr 2026 03:45:00 +0000

Type Values Removed Values Added
Title Infinite Loop in OpenBSD SLAACD and RAD Daemons Due to Zero-Length ICMPv6 ND Option

Tue, 21 Apr 2026 14:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 21 Apr 2026 00:00:00 +0000

Type Values Removed Values Added
First Time appeared Openbsd
Openbsd openbsd
Weaknesses CWE-1284
CPEs cpe:2.3:a:openbsd:openbsd:*:*:*:*:*:*:*:*
Vendors & Products Openbsd
Openbsd openbsd
Metrics cvssV3_1

{'score': 4.3, 'vector': 'CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L'}


Mon, 20 Apr 2026 23:30:00 +0000

Type Values Removed Values Added
Description In OpenBSD through 7.8, the slaacd and rad daemons have an infinite loop when they receive a crafted ICMPv6 Neighbor Discovery (ND) option (over a local network) with length zero, because of an "nd_opt_len * 8 - 2" expression with no preceding check for whether nd_opt_len is zero.
References

cve-icon MITRE

Status: PUBLISHED

Assigner: mitre

Published:

Updated: 2026-04-21T13:27:42.310Z

Reserved: 2026-04-20T00:00:00.000Z

Link: CVE-2026-41285

cve-icon Vulnrichment

Updated: 2026-04-21T13:27:37.961Z

cve-icon NVD

Status : Analyzed

Published: 2026-04-21T00:16:29.480

Modified: 2026-04-24T18:59:03.117

Link: CVE-2026-41285

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-04-28T16:30:35Z

Weaknesses