CVE-2026-55995
Description
A flaw was found in open-iscsi. An unauthenticated man-in-the-middle (MITM) attacker can exploit a double-free vulnerability in the iSNS attribute decoder. This can lead to a denial of service (DoS) condition, making the affected system unavailable.
Statement
This Important severity flaw in open-iscsi allows an unauthenticated Man-in-the-Middle (MITM) attacker to trigger a denial of service in the iSNS attribute decoder. The vulnerability is network-exploitable without requiring user interaction or authentication, posing a significant risk to the availability of iSNS services in environments where the isns-utils package is deployed and the iSNS service is exposed.
Mitigation
If the iSNS service is not actively used, disable it to prevent exploitation.
To disable the `isnsd` service, execute `systemctl disable --now isnsd`.
If the iSNS service is required, restrict network access to UDP port 3260 to only trusted hosts and networks using firewall rules.
A service restart may be required for changes to take effect.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 7.5 | N/A | N/A |
| Attack Vector | Network | N/A | N/A |
| Attack Complexity | Low | N/A | N/A |
| Privileges Required | None | N/A | N/A |
| User Interaction | None | N/A | N/A |
| Scope | Unchanged | N/A | N/A |
| Confidentiality | None | N/A | N/A |
| Integrity Impact | None | N/A | N/A |
| Availability Impact | High | N/A | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Integrity,Availability,Confidentiality
Technical Impact: Modify Memory; DoS: Crash, Exit, or Restart; Execute Unauthorized Code or Commands
This weakness may result in the corruption of memory, and perhaps instructions, possibly leading to a crash. If the corrupted memory can be effectively controlled, it may be possible to execute arbitrary code.
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