{"affected":[{"defaultStatus":"unaffected","ecosystem":"software-id","packageName":"otp","product":"OTP","source":"CNA: EEF","vendor":"Erlang","versions":[{"changes":[{"at":"26.2.5.18","status":"unaffected"},{"at":"27.3.4.9","status":"unaffected"},{"at":"28.4.1","status":"unaffected"}],"lessThan":"*","status":"affected","version":"17.0","versionType":"otp"}]},{"defaultStatus":"unaffected","ecosystem":"otp","packageName":"ssh","product":"OTP","source":"CNA: EEF","vendor":"Erlang","versions":[{"changes":[{"at":"5.1.4.14","status":"unaffected"},{"at":"5.2.11.6","status":"unaffected"},{"at":"5.5.1","status":"unaffected"}],"lessThan":"*","status":"affected","version":"3.0.1","versionType":"otp"}]},{"defaultStatus":"unaffected","ecosystem":"github","packageName":"erlang/otp","product":"OTP","source":"CNA: EEF","vendor":"Erlang","versions":[{"changes":[{"at":"0c1c04b191f6ab940e8fcfabce39eb5a8a6440a4","status":"unaffected"},{"at":"93073c3bd338c60cd2bae715ce6a1d4ffc1a8fd3","status":"unaffected"},{"at":"43a87b949bdff12d629a8c34146711d9da93b1b1","status":"unaffected"}],"lessThan":"*","status":"affected","version":"07b8f441ca711f9812fad9e9115bab3c3aa92f79","versionType":"git"}]}],"cveId":"CVE-2026-23943","cwes":["CWE-409"],"description":"Improper Handling of Highly Compressed Data (Compression Bomb) vulnerability in Erlang OTP ssh (ssh_transport modules) allows Denial of Service via Resource Depletion.\n\nThe 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.\n\nTwo compression algorithms are affected:\n\n* zlib: Activates immediately after key exchange, enabling unauthenticated attacks\n* zlib@openssh.com: Activates post-authentication, enabling authenticated attacks\n\nEach 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.\n\nThis 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.\n\nThis 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.","epss":{"date":"2026-11-10","percentile":0.54432,"score":0.00725},"exploits":[],"kev":null,"metrics":[{"score":6.9,"severity":"medium","source":"CNA: EEF","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N","version":"4.0"}],"modifiedAt":1794426254524,"publishedAt":1773393117794,"references":[{"source":"CNA: EEF","tags":["vendor-advisory","related"],"url":"https://github.com/erlang/otp/security/advisories/GHSA-c836-qprm-jw9r"},{"source":"CNA: EEF","tags":["related"],"url":"https://cna.erlef.org/cves/CVE-2026-23943.html"},{"source":"CNA: EEF","tags":["related"],"url":"https://osv.dev/vulnerability/EEF-CVE-2026-23943"},{"source":"CNA: EEF","tags":["x_version-scheme"],"url":"https://www.erlang.org/doc/system/versions.html#order-of-versions"},{"source":"CNA: EEF","tags":["related"],"url":"https://github.com/erlang/otp/commit/07b8f441ca711f9812fad9e9115bab3c3aa92f79"},{"source":"CNA: EEF","tags":["patch"],"url":"https://github.com/erlang/otp/commit/0c1c04b191f6ab940e8fcfabce39eb5a8a6440a4"},{"source":"CNA: EEF","tags":["patch"],"url":"https://github.com/erlang/otp/commit/93073c3bd338c60cd2bae715ce6a1d4ffc1a8fd3"},{"source":"CNA: EEF","tags":["patch"],"url":"https://github.com/erlang/otp/commit/43a87b949bdff12d629a8c34146711d9da93b1b1"}],"remediation":[{"kind":"workaround","source":"CNA: EEF","text":"Best workaround - Disable all compression:\n\n{preferred_algorithms, [{compression, ['none']}]}\n\nAlternative mitigations (less secure):\n\n* Disable only pre-auth zlib compression (authenticated users can still exploit via zlib@openssh.com):\n{modify_algorithms, [{rm, [{compression, ['zlib']}]}]}\n* Limit concurrent sessions (reduces attack surface but does not prevent exploitation):\n{max_sessions, N}  % Cap total concurrent sessions (default is infinity)"},{"kind":"fix","source":"CNA: EEF","text":"The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.","url":"https://github.com/erlang/otp/commit/0c1c04b191f6ab940e8fcfabce39eb5a8a6440a4"},{"kind":"fix","source":"CNA: EEF","text":"The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.","url":"https://github.com/erlang/otp/commit/93073c3bd338c60cd2bae715ce6a1d4ffc1a8fd3"},{"kind":"fix","source":"CNA: EEF","text":"The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches.","url":"https://github.com/erlang/otp/commit/43a87b949bdff12d629a8c34146711d9da93b1b1"}],"revision":"aafe007ea08bebad996c001f2083f3dc69df61e1a084bf6ca2a1449cd334288e","sources":[{"modifiedAt":1794426254524,"name":"CNA: EEF","retrievedAt":1794427750605,"url":"https://www.cve.org/CVERecord?id=CVE-2026-23943"},{"modifiedAt":null,"name":"FIRST EPSS","retrievedAt":1794427766393,"url":"https://api.first.org/data/v1/epss?cve=CVE-2026-23943"}],"ssvc":{"assessedAt":1773417700898,"automatable":"yes","exploitation":"none","source":"ADP: CISA-ADP","technicalImpact":"partial"},"status":"published","title":"Pre-auth SSH DoS via unbounded zlib inflate","updatedAt":1794427766393}