CVE-2026-54886
Description
A flaw was found in the Erlang OTP ssh (Secure Shell) component, specifically within its SFTP (SSH File Transfer Protocol) module. An authenticated SFTP user can exploit this vulnerability by sending specially crafted extended data on an open channel. This action triggers an infinite loop in the ssh_sftpd process, rendering the SFTP channel permanently unresponsive and leading to a denial of service (DoS). The affected process will continuously consume CPU resources and accumulate unbounded memory.
Statement
A denial-of-service vulnerability was found in the ssh_sftpd module of Erlang/OTP. An authenticated SFTP user can send SSH_MSG_CHANNEL_EXTENDED_DATA messages that trigger an infinite tail-recursive loop in the ssh_sftpd:handle_data/4 function, rendering the targeted SFTP channel permanently unresponsive, with secondary CPU and memory consumption.
Mitigation
Set the max_channels daemon option to a finite value instead of the default 'infinity' to limit the number of channels an authenticated user can open per connection, reducing the amplification potential of this vulnerability.
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 | 6.5 | 4.3 | N/A |
| Attack Vector | Network | Network | N/A |
| Attack Complexity | Low | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Unchanged | Unchanged | N/A |
| Confidentiality | None | None | N/A |
| Integrity Impact | None | None | N/A |
| Availability Impact | High | Low | N/A |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Amplification
An infinite loop will cause unexpected consumption of resources, such as CPU cycles or memory. The software's operation may slow down, or cause a long time to respond.
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