CVE-2026-58250
Description
A flaw was found in NATS Server, a high-performance messaging system. An unauthenticated attacker with network access to a leafnode listener, where compression is enabled, could exploit this vulnerability. By sending repeated leafnode INFO protocol messages during the pre-authentication handshake, the attacker can cause the server to crash. This leads to a Denial of Service (DoS), making the server unavailable to legitimate users.
Statement
This is an Important denial of service vulnerability in NATS Server. An unauthenticated remote attacker with network access to a leafnode listener, configured with compression enabled, could repeatedly send INFO protocol messages during the pre-authentication handshake. This action would cause the NATS server to crash, leading to a denial of service for legitimate users.
Mitigation
To reduce exposure, disable compression on NATS Server leafnode listeners if not strictly required for your environment. Alternatively, implement network access controls to restrict connectivity to leafnode listeners to only trusted clients. This limits the ability of unauthenticated peers to initiate the vulnerable handshake.
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 | 7.5 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | None | N/A | None |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
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