CVE-2026-68956

What it is

Allocation of Resources Without Limits or Throttling vulnerability in Erlang/OTP ssh allows an authenticated remote attacker to exhaust node memory by repeatedly opening session channels that are never assigned a handler. The "session" clause of ssh_connection:handle_msg/4 checks only minimal_remote_max_packet_size before calling setup_session/5, which unconditionally builds a #channel{} record and stores it in the ETS channel cache. The max_channels daemon option is consulted only by ssh_channel_sup:max_num_channels_not_exceeded/2, which counts supervisor children, so a channel that never gets a shell, exec, or subsystem handler is invisible to the limit and setting the option to a finite value does not mitigate the attack. RFC 4254 section 5.1 permits many session channels per connection, and each record costs only a few hundred bytes, so a single authenticated connection can accumulate channels until the node runs out of memory and the emulator terminates, affecting every application on it. No file contents, credentials, or write access are obtainable. This issue affects OTP from OTP 18.1.2 before OTP 27.3.4.18, OTP 28.5.0.7, and OTP 29.1.1, corresponding to ssh from 4.1.1 before 5.2.11.13, 5.5.2.6, and 6.0.6. Whether OTP before OTP 18.1.2, corresponding to ssh before 4.1.1, is affected is unknown.

At a glance

Exploitability

Can be exploited over the network with a low-privilege account. High risk of service disruption.

Exploit odds

0.4% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2026-09-22 09:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-09-24 21:17 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 0.4% in the next 30 days (EPSS).
• Severity: 7.1 HIGH (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2026-09-22 09:17 UTC

Last modified

2026-09-24 21:17 UTC

Exploit probability

0.4% · EPSS, next 30 days

Weakness

CWE-770 · Allocation without limits

Record status

Deferred

Attack profile CVSS 4.0 · 7.1

Attack vector

Network

Complexity

Low

Attack requirements

None

Privileges needed

Low

User interaction

None

Confidentiality

None

Integrity

None

Availability

High

Is it in your code?

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