| Name | 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 * 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. |
| Source | CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| References | DLA-4590-1 |
| Debian Bugs | 1130912 |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| erlang (PTS) | bullseye | 1:23.2.6+dfsg-1+deb11u1 | vulnerable |
| bullseye (security) | 1:23.2.6+dfsg-1+deb11u4 | fixed | |
| bookworm | 1:25.2.3+dfsg-1+deb12u4 | fixed | |
| bookworm (security) | 1:25.2.3+dfsg-1+deb12u1 | vulnerable | |
| trixie | 1:27.3.4.1+dfsg-1+deb13u2 | fixed | |
| forky, sid | 1:29.0.4+dfsg-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| erlang | source | bullseye | 1:23.2.6+dfsg-1+deb11u4 | DLA-4590-1 | ||
| erlang | source | bookworm | 1:25.2.3+dfsg-1+deb12u4 | |||
| erlang | source | trixie | 1:27.3.4.1+dfsg-1+deb13u2 | |||
| erlang | source | (unstable) | 1:27.3.4.9+dfsg-1 | 1130912 |
https://github.com/erlang/otp/security/advisories/GHSA-c836-qprm-jw9r
Fixed by: https://github.com/erlang/otp/commit/43a87b949bdff12d629a8c34146711d9da93b1b1 (OTP-28.4.1)
Fixed by: https://github.com/erlang/otp/commit/93073c3bd338c60cd2bae715ce6a1d4ffc1a8fd3 (OTP-27.3.4.9)
Fixed by: https://github.com/erlang/otp/commit/0c1c04b191f6ab940e8fcfabce39eb5a8a6440a4 (OTP-26.2.5.18)