CVE-2026-23943
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 before OTP 28.4.1, OTP 27.3.4.9 and OTP 26.2.5.18, corresponding to ssh from 3.0.1 before 5.5.1, 5.2.11.6 and 5.1.4.14.
How to fix
- erlang erlang\/otp26.2.5.18, 27.3.4.9, 28.4.1 or later
- erlang erlang\/ssh5.1.4.14, 5.2.11.6 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| erlang erlang\/otp | 17.0 ≤ v < 26.2.5.18, 27.0 ≤ v < 27.3.4.9, 28.0 ≤ v < 28.4.1 | 26.2.5.18, 27.3.4.9, 28.4.1 |
| erlang erlang\/ssh | 3.0.1 ≤ v < 5.1.4.14, 5.2 ≤ v < 5.2.11.6, 5.5 ≤ v ≤ 5.5.1 | 5.1.4.14, 5.2.11.6 |
Check your version
Choose the product and enter the version you run to see whether it falls in the affected range.
Attack Surface Management
See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.