Improper Handling of Highly Compressed Data (Compression Bomb) vulnerability in Erlang OTP ssh (ssh_transport modules) allows Denial of Service via Resource Depletion.

The SSH transport layer advertises legacy zlib compression by default and inflates attacker-controlled payloads pre-authentication without any size limit, enabling reliable memory exhaustion DoS.

Two compression algorithms are affected:

* zlib: Activates immediately after key exchange, enabling unauthenticated attacks
* [email protected]: Activates post-authentication, enabling authenticated attacks

Each SSH packet can decompress ~255 MB from 256 KB of wire data (1029:1 amplification ratio). Multiple packets can rapidly exhaust available memory, causing OOM kills in memory-constrained environments.

This vulnerability is associated with program files lib/ssh/src/ssh_transport.erl and program routines ssh_transport:decompress/2, ssh_transport:handle_packet_part/4.

This issue affects OTP from OTP 17.0 until OTP 28.4.1, 27.3.4.9 and 26.2.5.18 corresponding to ssh from 3.0.1 until 5.5.1, 5.2.11.6 and 5.1.4.14.
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.


Workaround

Best workaround - Disable all compression: {preferred_algorithms, [{compression, ['none']}]} Alternative mitigations (less secure): * Disable only pre-auth zlib compression (authenticated users can still exploit via [email protected]): {modify_algorithms, [{rm, [{compression, ['zlib']}]}]} * Limit concurrent sessions (reduces attack surface but does not prevent exploitation): {max_sessions, N} % Cap total concurrent sessions (default is infinity)

History

Mon, 16 Mar 2026 10:15:00 +0000

Type Values Removed Values Added
First Time appeared Erlang erlang/otp
Erlang otp
Vendors & Products Erlang erlang/otp
Erlang otp

Fri, 13 Mar 2026 16:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 13 Mar 2026 09:30:00 +0000

Type Values Removed Values Added
Description Improper Handling of Highly Compressed Data (Compression Bomb) vulnerability in Erlang OTP ssh (ssh_transport modules) allows Denial of Service via Resource Depletion. The SSH transport layer advertises legacy zlib compression by default and inflates attacker-controlled payloads pre-authentication without any size limit, enabling reliable memory exhaustion DoS. Two compression algorithms are affected: * zlib: Activates immediately after key exchange, enabling unauthenticated attacks * [email protected]: Activates post-authentication, enabling authenticated attacks Each SSH packet can decompress ~255 MB from 256 KB of wire data (1029:1 amplification ratio). Multiple packets can rapidly exhaust available memory, causing OOM kills in memory-constrained environments. This vulnerability is associated with program files lib/ssh/src/ssh_transport.erl and program routines ssh_transport:decompress/2, ssh_transport:handle_packet_part/4. This issue affects OTP from OTP 17.0 until OTP 28.4.1, 27.3.4.9 and 26.2.5.18 corresponding to ssh from 3.0.1 until 5.5.1, 5.2.11.6 and 5.1.4.14.
Title Pre-auth SSH DoS via unbounded zlib inflate
First Time appeared Erlang
Erlang erlang\/otp
Weaknesses CWE-409
CPEs cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
Vendors & Products Erlang
Erlang erlang\/otp
References
Metrics cvssV4_0

{'score': 6.9, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: EEF

Published:

Updated: 2026-03-13T16:07:55.970Z

Reserved: 2026-01-19T14:23:14.343Z

Link: CVE-2026-23943

cve-icon Vulnrichment

Updated: 2026-03-13T16:01:44.722Z

cve-icon NVD

Status : Awaiting Analysis

Published: 2026-03-13T19:54:15.783

Modified: 2026-03-16T14:54:11.293

Link: CVE-2026-23943

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-03-16T09:37:49Z

Weaknesses