{"id":"CVE-2026-122127","title":"CESNET ipfixcol2 2.7.1 before 2.9.0 Heap Buffer Overflow via TCP LZ4 Decoder","summary":"CESNET ipfixcol2 2.7.1 before 2.9.0 contains a heap-based buffer overflow in Lz4Decoder.cpp that allows unauthenticated network peers to write past heap buffers. Attackers can declare a small ring buffer_size followed by a large decompre…","severity":"high","cvss":7.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","cvssSource":"cna","cwe":["CWE-787"],"vendor":"CESNET","product":"ipfixcol2","affected":["ipfixcol2 >= 2.7.1 < 2.9.0"],"ssvc":{"exploitation":"none","automatable":"yes","technicalImpact":"partial","timestamp":"2026-11-05T19:34:44.874564Z"},"published":"2026-11-04","updated":"2026-11-05","sourceUpdated":"2026-11-05T19:36:14.196Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-122127","references":[{"url":"https://github.com/CESNET/ipfixcol2/commit/fd5cb168efb4b864d33f655174711b2779cef502","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#L139-L151"},{"url":"https://www.vulncheck.com/advisories/cesnet-ipfixcol2-2.7.1-before-2.9.0-heap-buffer-overflow-via-tcp-lz4-decoder","label":"VulnCheck Advisory: CESNET ipfixcol2 2.7.1 before 2.9.0 Heap Buffer Overflow via TCP LZ4 Decoder"}],"tags":["cve.org"],"epss":0.00387,"epssPercentile":0.32997,"ingestedAt":"2026-11-05T22:38:31.553Z","slug":"CVE-2026-122127","body":"## Overview\n\nCESNET ipfixcol2 2.7.1 before 2.9.0 contains a heap-based buffer overflow in Lz4Decoder.cpp that allows unauthenticated network peers to write past heap buffers. Attackers can declare a small ring buffer_size followed by a large decompressed_size to write up to 65535 controlled bytes and crash the collector.\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":"twilight","depthScore":41,"depthScoreParts":{"impact":41.3,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}