# CVE-2026-18726: Open-iscsi: open-iscsi: denial of service in iscsiuio router advertisement parsing

CVE-2026-18726 is fixed in 9 products on 1 platform, first by DEBIAN-CVE-2026-18726, released August 12, 2026. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2026-18726
- Priority: Routine
- CVSS: 6.5 (Moderate)
- EPSS: 0.0031
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Aug 12, 2026
- Weakness: Loop with Unreachable Exit Condition ('Infinite Loop')
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-18726

## Description

A flaw was found in open-iscsi. This vulnerability allows a remote attacker on the same local network segment to cause a Denial of Service (DoS) in the iscsiuio daemon. By sending a specially crafted Internet Control Message Protocol version 6 (ICMPv6) Router Advertisement with a zero-length option, the attacker can trigger an infinite loop. This leads to sustained CPU usage, rendering the daemon unresponsive and impacting system availability. A secondary risk of out-of-bounds reads exists with a short IPv6 payload, though no memory corruption or data exposure has been confirmed.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | iscsi-initiator-utils amzn 2023 | 6.2.1.4-10.git2a8f9d8.amzn2023.0.4 | [ALAS2023-2026-2120](https://patchblox.com/security/data/fix/linux/alas2023-2026-2120.md) | Aug 31, 2026 |
| Linux | iscsi-initiator-utils-debuginfo amzn 2023 | 6.2.1.4-10.git2a8f9d8.amzn2023.0.4 | [ALAS2023-2026-2120](https://patchblox.com/security/data/fix/linux/alas2023-2026-2120.md) | Aug 31, 2026 |
| Linux | iscsi-initiator-utils-debugsource amzn 2023 | 6.2.1.4-10.git2a8f9d8.amzn2023.0.4 | [ALAS2023-2026-2120](https://patchblox.com/security/data/fix/linux/alas2023-2026-2120.md) | Aug 31, 2026 |
| Linux | iscsi-initiator-utils-devel amzn 2023 | 6.2.1.4-10.git2a8f9d8.amzn2023.0.4 | [ALAS2023-2026-2120](https://patchblox.com/security/data/fix/linux/alas2023-2026-2120.md) | Aug 31, 2026 |
| Linux | iscsi-initiator-utils-iscsiuio amzn 2023 | 6.2.1.4-10.git2a8f9d8.amzn2023.0.4 | [ALAS2023-2026-2120](https://patchblox.com/security/data/fix/linux/alas2023-2026-2120.md) | Aug 31, 2026 |
| Linux | iscsi-initiator-utils-iscsiuio-debuginfo amzn 2023 | 6.2.1.4-10.git2a8f9d8.amzn2023.0.4 | [ALAS2023-2026-2120](https://patchblox.com/security/data/fix/linux/alas2023-2026-2120.md) | Aug 31, 2026 |
| Linux | open-iscsi Debian 12.15 (bookworm) | 2.1.8-1+deb12u1 | [DEBIAN-CVE-2026-18726](https://patchblox.com/security/data/fix/linux/debian-cve-2026-18726.md) | Aug 12, 2026 |
| Linux | open-iscsi Debian 14 | 2.1.13-1 | [DEBIAN-CVE-2026-18726](https://patchblox.com/security/data/fix/linux/debian-cve-2026-18726.md) | Aug 12, 2026 |
| Linux | python3-iscsi-initiator-utils amzn 2023 | 6.2.1.4-10.git2a8f9d8.amzn2023.0.4 | [ALAS2023-2026-2120](https://patchblox.com/security/data/fix/linux/alas2023-2026-2120.md) | Aug 31, 2026 |
| Linux | python3-iscsi-initiator-utils-debuginfo amzn 2023 | 6.2.1.4-10.git2a8f9d8.amzn2023.0.4 | [ALAS2023-2026-2120](https://patchblox.com/security/data/fix/linux/alas2023-2026-2120.md) | Aug 31, 2026 |

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Data as of 2026-11-09T01:18:40Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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