{"id":"CVE-2026-23943","title":"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 defaul…","summary":"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 defaul…","severity":"medium","cvss":5.3,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L","cwe":["CWE-409"],"vendor":"erlang","product":"erlang/otp","affected":["erlang/otp >= 17.0, < 26.2.5.18","erlang/otp >= 27.0, < 27.3.4.9","erlang/otp >= 28.0, < 28.4.1","erlang/ssh >= 3.0.1, < 5.1.4.14","erlang/ssh >= 5.2, < 5.2.11.6","erlang/ssh >= 5.5, <= 5.5.1"],"patched":["erlang/otp 28.4.1","erlang/ssh 5.2.11.6"],"published":"2026-03-13","updated":"2026-07-24","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-23943","references":[{"url":"https://cna.erlef.org/cves/CVE-2026-23943.html","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://github.com/erlang/otp/commit/0c1c04b191f6ab940e8fcfabce39eb5a8a6440a4","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://github.com/erlang/otp/commit/43a87b949bdff12d629a8c34146711d9da93b1b1","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://github.com/erlang/otp/commit/93073c3bd338c60cd2bae715ce6a1d4ffc1a8fd3","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://github.com/erlang/otp/security/advisories/GHSA-c836-qprm-jw9r","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://osv.dev/vulnerability/EEF-CVE-2026-23943","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"},{"url":"https://www.erlang.org/doc/system/versions.html#order-of-versions","label":"6b3ad84c-e1a6-4bf7-a703-f496b71e49db"}],"tags":["nvd"],"epss":0.00644,"epssPercentile":0.49134,"ingestedAt":"2026-07-24T15:30:58.218Z","slug":"CVE-2026-23943","body":"## Overview\n\nImproper 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 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.\n\n## Affected\n\n- `erlang/otp >= 17.0, < 26.2.5.18`\n- `erlang/otp >= 27.0, < 27.3.4.9`\n- `erlang/otp >= 28.0, < 28.4.1`\n- `erlang/ssh >= 3.0.1, < 5.1.4.14`\n- `erlang/ssh >= 5.2, < 5.2.11.6`\n- `erlang/ssh >= 5.5, <= 5.5.1`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `erlang/otp 28.4.1`\n- `erlang/ssh 5.2.11.6`","depth":"sunlit","depthScore":29,"depthScoreParts":{"impact":29.2,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}