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.
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Affected products
6- osv-coords2 versionspkg:rpm/opensuse/erlang27&distro=openSUSE%20Tumbleweedpkg:rpm/opensuse/erlang&distro=openSUSE%20Leap%2016.0
< 27.1.3-2.1+ 1 more
- (no CPE)range: < 27.1.3-2.1
- (no CPE)range: < 27.1.3-160000.4.1
Patches
Vulnerability mechanics
References
7- github.com/erlang/otp/commit/0c1c04b191f6ab940e8fcfabce39eb5a8a6440a4nvdPatch
- github.com/erlang/otp/commit/43a87b949bdff12d629a8c34146711d9da93b1b1nvdPatch
- github.com/erlang/otp/commit/93073c3bd338c60cd2bae715ce6a1d4ffc1a8fd3nvdPatch
- cna.erlef.org/cves/CVE-2026-23943.htmlnvdVendor Advisory
- github.com/erlang/otp/security/advisories/GHSA-c836-qprm-jw9rnvdVendor Advisory
- osv.dev/vulnerability/EEF-CVE-2026-23943nvdThird Party Advisory
- www.erlang.org/doc/system/versions.htmlnvdProduct
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