{"id":"CVE-2026-122129","title":"CESNET ipfixcol2 2.7.1 before 2.9.0 Memory Exhaustion via TCP LZ4 Decoder","summary":"CESNET ipfixcol2 2.7.1 before 2.9.0 contains a memory allocation vulnerability in Lz4Decoder::read_start_header() that allows unauthenticated attackers to exhaust memory by declaring unbounded ring buffer sizes. Attackers can open TCP co…","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","cvssSource":"cna","cwe":["CWE-789"],"vendor":"CESNET","product":"ipfixcol2","affected":["ipfixcol2 >= 2.7.1 < 2.9.0"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-11-05T20:48:38.242757Z"},"published":"2026-11-04","updated":"2026-11-05","sourceUpdated":"2026-11-05T20:48:47.204Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-122129","references":[{"url":"https://github.com/CESNET/ipfixcol2/commit/1a199033eff847941353c5c039cb806a9ad8aa6f","label":"Patch Commit"},{"url":"https://github.com/CESNET/ipfixcol2"},{"url":"https://github.com/CESNET/ipfixcol2/releases/tag/v2.9.0","label":"ipfixcol2 v2.9.0 Release Notes"},{"url":"https://github.com/CESNET/ipfixcol2/blob/v2.8.0/src/plugins/input/tcp/src/Lz4Decoder.cpp#L126-L131"},{"url":"https://www.vulncheck.com/advisories/cesnet-ipfixcol2-2.7.1-before-2.9.0-memory-exhaustion-via-tcp-lz4-decoder","label":"VulnCheck Advisory: CESNET ipfixcol2 2.7.1 before 2.9.0 Memory Exhaustion via TCP LZ4 Decoder"}],"tags":["cve.org"],"epss":0.00401,"epssPercentile":0.34581,"ingestedAt":"2026-11-05T22:38:31.885Z","slug":"CVE-2026-122129","body":"## Overview\n\nCESNET ipfixcol2 2.7.1 before 2.9.0 contains a memory allocation vulnerability in Lz4Decoder::read_start_header() that allows unauthenticated attackers to exhaust memory by declaring unbounded ring buffer sizes. Attackers can open TCP connections sending LZ4 start headers with very large buffer sizes, forcing up to 4 GiB allocations per connection and denying collector service.\n\n## Affected\n\n- `ipfixcol2 >= 2.7.1 < 2.9.0`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":29,"depthScoreParts":{"impact":29.2,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}