CVE-2026-23943

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Source
https://cve.org/CVERecord?id=CVE-2026-23943
Import Source
https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-23943.json
JSON Data
https://api.test.osv.dev/v1/vulns/CVE-2026-23943
Aliases
Downstream
AZL (1)
DEBIAN (1)
OESA (5)
openSUSE (2)
SUSE (3)
UBUNTU (1)
Related
openSUSE (2)
SUSE (3)
Published
2026-03-13T09:11:57Z
Modified
2026-10-22T10:34:18Z
Severity
  • 6.9 (Medium) CVSS_V4 - 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 CVSS Calculator
Summary
Pre-auth SSH DoS via unbounded zlib inflate
Details

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 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.

Database specific 
{
    "cna_assigner": "EEF",
    "cwe_ids": [
        "CWE-409"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23943.json",
    "unresolved_ranges": [
        {
            "extracted_events": [
                {
                    "range": [
                        {
                            "introduced": "3.0.1"
                        },
                        {
                            "fixed": "5.5.1"
                        }
                    ],
                    "source": "AFFECTED_FIELD",
                    "strategy": "ChangesAt"
                }
            ]
        }
    ]
}
References

Affected packages

Git / github.com/erlang/otp

Affected ranges

Type
GIT
Repo
https://github.com/erlang/otp
Events
Introduced
07b8f441ca711f9812fad9e9115bab3c3aa92f79
Fixed
8c304e09e4d9301f56f6d7b2c4c9f60b4f9d9425
Introduced
601a012837ea0a5c8095bf24223132824177124d
Fixed
4aa809ae4eb4a20ad89c23837376acf179877f39
Introduced
9e6f6742c4d9e9915ee8af0dcb7d97cf1f836116
Fixed
c8fca7e34e4db5d977ccf292cc2490ddb05b5879
Fixed
0c1c04b191f6ab940e8fcfabce39eb5a8a6440a4
Fixed
43a87b949bdff12d629a8c34146711d9da93b1b1
Fixed
93073c3bd338c60cd2bae715ce6a1d4ffc1a8fd3
Database specific
Show details 
{
    "extracted_events": [
        {
            "cpe": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*",
            "range": [
                {
                    "introduced": "17.0"
                },
                {
                    "fixed": "26.2.5.18"
                }
            ],
            "source": "CPE_RANGE"
        },
        {
            "cpe": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*",
            "range": [
                {
                    "introduced": "27.0"
                },
                {
                    "fixed": "27.3.4.9"
                }
            ],
            "source": "CPE_RANGE"
        },
        {
            "cpe": "cpe:2.3:a:erlang:erlang\\/otp:*:*:*:*:*:*:*:*",
            "range": [
                {
                    "introduced": "28.0"
                },
                {
                    "fixed": "28.4.1"
                }
            ],
            "source": "CPE_RANGE"
        },
        {
            "range": [
                {
                    "fixed": "0c1c04b191f6ab940e8fcfabce39eb5a8a6440a4"
                }
            ],
            "source": "REFERENCES_COMMIT"
        },
        {
            "range": [
                {
                    "fixed": "43a87b949bdff12d629a8c34146711d9da93b1b1"
                }
            ],
            "source": "REFERENCES_COMMIT"
        },
        {
            "range": [
                {
                    "fixed": "93073c3bd338c60cd2bae715ce6a1d4ffc1a8fd3"
                }
            ],
            "source": "REFERENCES_COMMIT"
        }
    ]
}

Affected versions

OTP-17.*
OTP-17.0
OTP-18.*
OTP-18.0
OTP-18.0-rc1
OTP-19.*
OTP-19.0
OTP-19.0-rc1
OTP-19.0-rc2
OTP-20.*
OTP-20.0
OTP-20.0-rc1
OTP-20.0-rc2
OTP-21.*
OTP-21.0
OTP-21.0-rc1
OTP-21.0-rc2
OTP-22.*
OTP-22.0
OTP-22.0-rc1
OTP-22.0-rc2
OTP-22.0-rc3
OTP-23.*
OTP-23.0
OTP-23.0-rc1
OTP-23.0-rc2
OTP-23.0-rc3
OTP-24.*
OTP-24.0
OTP-24.0-rc1
OTP-24.0-rc2
OTP-24.0-rc3
OTP-25.*
OTP-25.0
OTP-25.0-rc1
OTP-25.0-rc2
OTP-25.0-rc3
OTP-26.*
OTP-26.0
OTP-26.0-rc1
OTP-26.0-rc2
OTP-26.0-rc3
OTP-26.1
OTP-26.2
OTP-26.2.3
OTP-26.2.4
OTP-26.2.5
OTP-26.2.5.1
OTP-26.2.5.10
OTP-26.2.5.11
OTP-26.2.5.12
OTP-26.2.5.13
OTP-26.2.5.14
OTP-26.2.5.15
OTP-26.2.5.16
OTP-26.2.5.17
OTP-26.2.5.2
OTP-26.2.5.3
OTP-26.2.5.4
OTP-26.2.5.5
OTP-26.2.5.6
OTP-26.2.5.7
OTP-26.2.5.8
OTP-26.2.5.9
OTP-27.*
OTP-27.0
OTP-27.1
OTP-27.2
OTP-27.3
OTP-27.3.1
OTP-27.3.2
OTP-27.3.3
OTP-27.3.4
OTP-27.3.4.1
OTP-27.3.4.2
OTP-27.3.4.3
OTP-27.3.4.4
OTP-27.3.4.5
OTP-27.3.4.6
OTP-27.3.4.7
OTP-27.3.4.8
OTP-28.*
OTP-28.0
OTP-28.1
OTP-28.4
Other
patch-base-26
patch-base-27

Database specific

source 
"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-23943.json"