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CVE PROGRAM SOURCE RECORD6.9 Medium

CVE-2026-23943

Pre-auth SSH DoS via unbounded zlib inflate

Read JSON ↗CVE.org ↗
Status
Published
Published
Updated
Assigning organization
EEF

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 * zlib@openssh.com: 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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Erlang OTP

Default version status: unknown

  • 3.0.1 to < *affected
pkg:otp/ssh?repository_url=https:%2F%2Fgithub.com%2Ferlang%2Fotp&vcs_url=git%20https:%2F%2Fgithub.com%2Ferlang%2Fotp.git

Erlang OTP

Default version status: unknown

  • 17.0 to < *affected
  • 07b8f441ca711f9812fad9e9115bab3c3aa92f79 to < *affected
pkg:github/erlang/otp

References