CVE-2026-23943

01/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 26.2.5.18, OTP 27.3.4.9, and OTP 28.4.1, corresponding to ssh from 3.0.1 before 5.1.4.14, 5.2.11.6, and 5.5.1.

02/Affected products

erlang: erlang\/otp; erlang: erlang\/ssh

03/References8

• cna.erlef.org/cves/CVE-2026-23943.html Vendor Advisory
• github.com/erlang/otp/security/advisories/GHSA-c836-qprm-jw9r Vendor Advisory
• github.com/erlang/otp/commit/0c1c04b191f6ab940e8fcfabce39eb5a8a… Patch
• github.com/erlang/otp/commit/43a87b949bdff12d629a8c34146711d9da… Patch
• github.com/erlang/otp/commit/93073c3bd338c60cd2bae715ce6a1d4ffc… Patch
• github.com/erlang/otp/commit/07b8f441ca711f9812fad9e9115bab3c3a…
• osv.dev/vulnerability/EEF-CVE-2026-23943 Third Party Advisory
• www.erlang.org/doc/system/versions.html#order-of-versions Product