{
    "dataType": "CVE_RECORD",
    "dataVersion": "5.2",
    "cveMetadata": {
        "cveId": "CVE-2026-23943",
        "assignerOrgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "state": "PUBLISHED",
        "assignerShortName": "EEF",
        "dateReserved": "2026-01-19T14:23:14.343Z",
        "datePublished": "2026-03-13T09:11:57.794Z",
        "dateUpdated": "2026-07-24T14:15:38.635Z"
    },
    "containers": {
        "cna": {
            "affected": [
                {
                    "cpes": [
                        "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"
                    ],
                    "defaultStatus": "unknown",
                    "modules": [
                        "ssh_transport"
                    ],
                    "packageName": "ssh",
                    "packageURL": "pkg:otp/ssh?repository_url=https:%2F%2Fgithub.com%2Ferlang%2Fotp&vcs_url=git%20https:%2F%2Fgithub.com%2Ferlang%2Fotp.git",
                    "product": "OTP",
                    "programFiles": [
                        "src/ssh_transport.erl"
                    ],
                    "programRoutines": [
                        {
                            "name": "ssh_transport:decompress/2"
                        },
                        {
                            "name": "ssh_transport:handle_packet_part/4"
                        }
                    ],
                    "repo": "https://github.com/erlang/otp",
                    "vendor": "Erlang",
                    "versions": [
                        {
                            "changes": [
                                {
                                    "at": "5.5.1",
                                    "status": "unaffected"
                                },
                                {
                                    "at": "5.2.11.6",
                                    "status": "unaffected"
                                },
                                {
                                    "at": "5.1.4.14",
                                    "status": "unaffected"
                                }
                            ],
                            "lessThan": "*",
                            "status": "affected",
                            "version": "3.0.1",
                            "versionType": "otp"
                        }
                    ]
                },
                {
                    "collectionURL": "https://github.com",
                    "cpes": [
                        "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*"
                    ],
                    "defaultStatus": "unknown",
                    "modules": [
                        "ssh_transport"
                    ],
                    "packageName": "erlang/otp",
                    "packageURL": "pkg:github/erlang/otp",
                    "product": "OTP",
                    "programFiles": [
                        "lib/ssh/src/ssh_transport.erl"
                    ],
                    "programRoutines": [
                        {
                            "name": "ssh_transport:decompress/2"
                        },
                        {
                            "name": "ssh_transport:handle_packet_part/4"
                        }
                    ],
                    "repo": "https://github.com/erlang/otp",
                    "vendor": "Erlang",
                    "versions": [
                        {
                            "changes": [
                                {
                                    "at": "28.4.1",
                                    "status": "unaffected"
                                },
                                {
                                    "at": "27.3.4.9",
                                    "status": "unaffected"
                                },
                                {
                                    "at": "26.2.5.18",
                                    "status": "unaffected"
                                }
                            ],
                            "lessThan": "*",
                            "status": "affected",
                            "version": "17.0",
                            "versionType": "otp"
                        },
                        {
                            "changes": [
                                {
                                    "at": "43a87b949bdff12d629a8c34146711d9da93b1b1",
                                    "status": "unaffected"
                                },
                                {
                                    "at": "93073c3bd338c60cd2bae715ce6a1d4ffc1a8fd3",
                                    "status": "unaffected"
                                },
                                {
                                    "at": "0c1c04b191f6ab940e8fcfabce39eb5a8a6440a4",
                                    "status": "unaffected"
                                }
                            ],
                            "lessThan": "*",
                            "status": "affected",
                            "version": "07b8f441ca711f9812fad9e9115bab3c3aa92f79",
                            "versionType": "git"
                        }
                    ]
                }
            ],
            "configurations": [
                {
                    "lang": "en",
                    "supportingMedia": [
                        {
                            "base64": false,
                            "type": "text/html",
                            "value": "The SSH server or client must advertise <tt>zlib</tt> or <tt>zlib@openssh.com</tt> compression. Both are enabled by default. With <tt>zlib</tt>, the attack is pre-authentication; with <tt>zlib@openssh.com</tt>, authentication is required first."
                        }
                    ],
                    "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."
                }
            ],
            "cpeApplicability": [
                {
                    "nodes": [
                        {
                            "cpeMatch": [
                                {
                                    "criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*",
                                    "versionEndExcluding": "26.2.5.18",
                                    "vulnerable": true
                                },
                                {
                                    "criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*",
                                    "versionEndExcluding": "27.3.4.9",
                                    "versionStartIncluding": "27.0",
                                    "vulnerable": true
                                },
                                {
                                    "criteria": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*",
                                    "versionEndExcluding": "28.4.1",
                                    "versionStartIncluding": "28.0",
                                    "vulnerable": true
                                }
                            ],
                            "negate": false,
                            "operator": "OR"
                        }
                    ],
                    "operator": "AND"
                }
            ],
            "credits": [
                {
                    "lang": "en",
                    "type": "finder",
                    "value": "Igor Morgenstern / Aisle Research"
                },
                {
                    "lang": "en",
                    "type": "remediation developer",
                    "value": "Michał Wąsowski"
                },
                {
                    "lang": "en",
                    "type": "remediation reviewer",
                    "value": "Jakub Witczak"
                }
            ],
            "descriptions": [
                {
                    "lang": "en",
                    "supportingMedia": [
                        {
                            "base64": false,
                            "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.<p>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.</p><p>Two compression algorithms are affected:</p><ul><li><b>zlib:</b> Activates immediately after key exchange, enabling unauthenticated attacks</li><li><b>zlib@openssh.com:</b> Activates post-authentication, enabling authenticated attacks</li></ul><p>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.</p><p>This vulnerability is associated with program files <tt>lib/ssh/src/ssh_transport.erl</tt> and program routines <tt>ssh_transport:decompress/2</tt>, <tt>ssh_transport:handle_packet_part/4</tt>.</p><p>This issue affects OTP from OTP 17.0 before OTP&nbsp;28.4.1, OTP&nbsp;27.3.4.9 and OTP&nbsp;26.2.5.18, corresponding to ssh from 3.0.1 before 5.5.1, 5.2.11.6 and 5.1.4.14.</p>"
                        }
                    ],
                    "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 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."
                }
            ],
            "impacts": [
                {
                    "capecId": "CAPEC-130",
                    "descriptions": [
                        {
                            "lang": "en",
                            "value": "CAPEC-130 Excessive Allocation"
                        }
                    ]
                },
                {
                    "capecId": "CAPEC-490",
                    "descriptions": [
                        {
                            "lang": "en",
                            "value": "CAPEC-490 Amplification"
                        }
                    ]
                }
            ],
            "metrics": [
                {
                    "cvssV4_0": {
                        "Automatable": "NOT_DEFINED",
                        "Recovery": "NOT_DEFINED",
                        "Safety": "NOT_DEFINED",
                        "attackComplexity": "LOW",
                        "attackRequirements": "NONE",
                        "attackVector": "NETWORK",
                        "baseScore": 6.9,
                        "baseSeverity": "MEDIUM",
                        "exploitMaturity": "NOT_DEFINED",
                        "privilegesRequired": "NONE",
                        "providerUrgency": "NOT_DEFINED",
                        "subAvailabilityImpact": "NONE",
                        "subConfidentialityImpact": "NONE",
                        "subIntegrityImpact": "NONE",
                        "userInteraction": "NONE",
                        "valueDensity": "NOT_DEFINED",
                        "vectorString": "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",
                        "vulnAvailabilityImpact": "LOW",
                        "vulnConfidentialityImpact": "NONE",
                        "vulnIntegrityImpact": "NONE",
                        "vulnerabilityResponseEffort": "NOT_DEFINED"
                    },
                    "format": "CVSS",
                    "scenarios": [
                        {
                            "lang": "en",
                            "value": "GENERAL"
                        }
                    ]
                }
            ],
            "problemTypes": [
                {
                    "descriptions": [
                        {
                            "cweId": "CWE-409",
                            "description": "CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)",
                            "lang": "en",
                            "type": "CWE"
                        }
                    ]
                }
            ],
            "providerMetadata": {
                "orgId": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
                "shortName": "EEF",
                "dateUpdated": "2026-07-24T14:15:38.635Z"
            },
            "references": [
                {
                    "tags": [
                        "vendor-advisory",
                        "related"
                    ],
                    "url": "https://github.com/erlang/otp/security/advisories/GHSA-c836-qprm-jw9r"
                },
                {
                    "tags": [
                        "related"
                    ],
                    "url": "https://cna.erlef.org/cves/CVE-2026-23943.html"
                },
                {
                    "tags": [
                        "related"
                    ],
                    "url": "https://osv.dev/vulnerability/EEF-CVE-2026-23943"
                },
                {
                    "tags": [
                        "x_version-scheme"
                    ],
                    "url": "https://www.erlang.org/doc/system/versions.html#order-of-versions"
                },
                {
                    "tags": [
                        "patch"
                    ],
                    "url": "https://github.com/erlang/otp/commit/43a87b949bdff12d629a8c34146711d9da93b1b1"
                },
                {
                    "tags": [
                        "patch"
                    ],
                    "url": "https://github.com/erlang/otp/commit/93073c3bd338c60cd2bae715ce6a1d4ffc1a8fd3"
                },
                {
                    "tags": [
                        "patch"
                    ],
                    "url": "https://github.com/erlang/otp/commit/0c1c04b191f6ab940e8fcfabce39eb5a8a6440a4"
                }
            ],
            "source": {
                "discovery": "EXTERNAL"
            },
            "title": "Pre-auth SSH DoS via unbounded zlib inflate",
            "workarounds": [
                {
                    "lang": "en",
                    "supportingMedia": [
                        {
                            "base64": false,
                            "type": "text/html",
                            "value": "<p><b>Best workaround - Disable all compression:</b></p><pre>{preferred_algorithms, [{compression, ['none']}]}</pre><p><b>Alternative mitigations (less secure):</b></p><ul><li>Disable only pre-auth zlib compression (authenticated users can still exploit via zlib@openssh.com):<pre>{modify_algorithms, [{rm, [{compression, ['zlib']}]}]}</pre></li><li>Limit concurrent sessions (reduces attack surface but does not prevent exploitation):<pre>{max_sessions, N}  % Cap total concurrent sessions (default is infinity)</pre></li></ul>"
                        }
                    ],
                    "value": "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)"
                }
            ],
            "x_generator": {
                "engine": "Vulnogram 0.2.0"
            }
        },
        "adp": [
            {
                "metrics": [
                    {
                        "other": {
                            "type": "ssvc",
                            "content": {
                                "timestamp": "2026-03-13T16:01:40.898658Z",
                                "id": "CVE-2026-23943",
                                "options": [
                                    {
                                        "Exploitation": "none"
                                    },
                                    {
                                        "Automatable": "yes"
                                    },
                                    {
                                        "Technical Impact": "partial"
                                    }
                                ],
                                "role": "CISA Coordinator",
                                "version": "2.0.3"
                            }
                        }
                    }
                ],
                "title": "CISA ADP Vulnrichment",
                "providerMetadata": {
                    "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
                    "shortName": "CISA-ADP",
                    "dateUpdated": "2026-03-13T16:01:48.609Z"
                }
            }
        ]
    }
}