CVE-2026-23943 (GCVE-0-2026-23943)
Vulnerability from cvelistv5
Published
2026-03-13 09:11
Modified
2026-04-07 14:38
Severity ?
6.9 (Medium) - 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
CWE
  • CWE-409 - Improper Handling of Highly Compressed Data (Data Amplification)
Summary
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.
References
Impacted products
Vendor Product Version
Erlang OTP Version: 3.0.1
    cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
 Create a notification for this product.
   Erlang OTP Version: 17.0
Version: 07b8f441ca711f9812fad9e9115bab3c3aa92f79
    cpe:2.3:a:erlang:erlang\/otp:*:*:*:*:*:*:*:*
 Create a notification for this product.
Show details on NVD website

To clipboard 

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              "value": "Improper Handling of Highly Compressed Data (Compression Bomb) vulnerability in Erlang OTP ssh (ssh_transport modules) allows Denial of Service via Resource Depletion.\u003cp\u003eThe 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.\u003c/p\u003e\u003cp\u003eTwo compression algorithms are affected:\u003c/p\u003e\u003cul\u003e\u003cli\u003e\u003cb\u003ezlib:\u003c/b\u003e Activates immediately after key exchange, enabling unauthenticated attacks\u003c/li\u003e\u003cli\u003e\u003cb\u003ezlib@openssh.com:\u003c/b\u003e Activates post-authentication, enabling authenticated attacks\u003c/li\u003e\u003c/ul\u003e\u003cp\u003eEach 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.\u003c/p\u003e\u003cp\u003eThis vulnerability is associated with program files \u003ctt\u003elib/ssh/src/ssh_transport.erl\u003c/tt\u003e and program routines \u003ctt\u003essh_transport:decompress/2\u003c/tt\u003e, \u003ctt\u003essh_transport:handle_packet_part/4\u003c/tt\u003e.\u003c/p\u003e\u003cp\u003eThis 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.\u003c/p\u003e"
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zlib@openssh.com):\u003cpre\u003e{modify_algorithms, [{rm, [{compression, [\u0027zlib\u0027]}]}]}\u003c/pre\u003e\u003c/li\u003e\u003cli\u003eLimit concurrent sessions (reduces attack surface but does not prevent exploitation):\u003cpre\u003e{max_sessions, N}  % Cap total concurrent sessions (default is infinity)\u003c/pre\u003e\u003c/li\u003e\u003c/ul\u003e\", \"base64\": false}]}], \"x_generator\": {\"engine\": \"Vulnogram 0.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"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 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.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"Improper Handling of Highly Compressed Data (Compression Bomb) vulnerability in Erlang OTP ssh (ssh_transport modules) allows Denial of Service via Resource Depletion.\u003cp\u003eThe 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.\u003c/p\u003e\u003cp\u003eTwo compression algorithms are affected:\u003c/p\u003e\u003cul\u003e\u003cli\u003e\u003cb\u003ezlib:\u003c/b\u003e Activates immediately after key exchange, enabling unauthenticated attacks\u003c/li\u003e\u003cli\u003e\u003cb\u003ezlib@openssh.com:\u003c/b\u003e Activates post-authentication, enabling authenticated attacks\u003c/li\u003e\u003c/ul\u003e\u003cp\u003eEach 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.\u003c/p\u003e\u003cp\u003eThis vulnerability is associated with program files \u003ctt\u003elib/ssh/src/ssh_transport.erl\u003c/tt\u003e and program routines \u003ctt\u003essh_transport:decompress/2\u003c/tt\u003e, \u003ctt\u003essh_transport:handle_packet_part/4\u003c/tt\u003e.\u003c/p\u003e\u003cp\u003eThis 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.\u003c/p\u003e\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-409\", \"description\": \"CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)\"}]}], \"configurations\": [{\"lang\": \"en\", \"value\": \"The SSH server or client must advertise zlib or zlib@openssh.com compression. Both are enabled by default. With zlib, the attack is pre-authentication; with zlib@openssh.com, authentication is required first.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"The SSH server or client must advertise \u003ctt\u003ezlib\u003c/tt\u003e or \u003ctt\u003ezlib@openssh.com\u003c/tt\u003e compression. Both are enabled by default. With \u003ctt\u003ezlib\u003c/tt\u003e, the attack is pre-authentication; with \u003ctt\u003ezlib@openssh.com\u003c/tt\u003e, authentication is required first.\", \"base64\": false}]}], \"providerMetadata\": {\"orgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"shortName\": \"EEF\", \"dateUpdated\": \"2026-04-07T14:38:05.652Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-23943\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-04-07T14:38:05.652Z\", \"dateReserved\": \"2026-01-19T14:23:14.343Z\", \"assignerOrgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"datePublished\": \"2026-03-13T09:11:57.794Z\", \"assignerShortName\": \"EEF\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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