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 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.
Predictions
Heuristic predictions, AS-IS, for prioritization only.
Mitigations
No mitigations published for this CVE yet.
The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.
✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here withsource_tier=community-verified.
OS impact
| OS | Version | Status | Fixed in |
|---|---|---|---|
| debian | bookworm | fixed | 1:25.2.3+dfsg-1+deb12u4 |
| debian | bullseye | fixed | 1:23.2.6+dfsg-1+deb11u4 |
| debian | forky | fixed | 1:27.3.4.9+dfsg-1 |
| debian | sid | fixed | 1:27.3.4.9+dfsg-1 |
| debian | trixie | fixed | 1:27.3.4.1+dfsg-1+deb13u2 |
| sles | affected | |
Application impact
| Vendor | Product | Versions | Fixed |
|---|---|---|---|
| erlang | erlang\/otp | {"startIncluding":"17.0","endExcluding":"26.2.5.18"} | 26.2.5.18 |
| erlang | erlang\/ssh | {"startIncluding":"3.0.1","endExcluding":"5.1.4.14"} | 5.1.4.14 |
References
- https://github.com/erlang/otp/security/advisories/GHSA-c836-qprm-jw9r
- https://cna.erlef.org/cves/CVE-2026-23943.html
- https://osv.dev/vulnerability/EEF-CVE-2026-23943
- https://www.erlang.org/doc/system/versions.html#order-of-versions
- https://github.com/erlang/otp/commit/43a87b949bdff12d629a8c34146711d9da93b1b1
- https://github.com/erlang/otp/commit/93073c3bd338c60cd2bae715ce6a1d4ffc1a8fd3
- https://github.com/erlang/otp/commit/0c1c04b191f6ab940e8fcfabce39eb5a8a6440a4
- https://security-tracker.debian.org/tracker/CVE-2026-23943
- https://www.suse.com/security/cve/CVE-2026-23943.html
CWEs
CWE-409
Community-verified mitigations for this CVE will appear above when contributors publish them.
Verify integrity in audit chain (admin only). AS-IS.