CVE-2026-122127— CESNET ipfixcol2 2.7.1 before 2.9.0 Heap Buffer Overflow via TCP LZ4 Decoder

Quick assessment

Affected

CESNET ipfixcol2

Exploitation

No confirmed in-the-wild exploitation; assess based on exposure

Recommended action

Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 2.9.0 之前的 CESNET ipfixcol2 2.7.1 版本中，Lz4Decoder.cpp 文件存在堆缓冲区溢出漏洞。该漏洞允许未经身份验证的网络对等方向堆缓冲区之外写入数据。攻击者可通过声明一个较小的环形缓冲区大小（ring buffer_size），随后指定一个较大的解压后数据大小（decompressed_size），从而写入多达 65535 个受控字节，导致采集器（collector）崩溃。

CVSS 7.5 · High Updated Nov 05, 2026

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

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Vulnerability Information

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Vulnerability Title

CESNET ipfixcol2 2.7.1 before 2.9.0 Heap Buffer Overflow via TCP LZ4 Decoder

Source: CVE Program / CVE List V5

Vulnerability Description

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 decompressed_size to write up to 65535 controlled bytes and crash the collector.

Source: CVE Program / CVE List V5

CVSS Information

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Source: CVE Program / CVE List V5

Vulnerability Type

跨界内存写

Source: CVE Program / CVE List V5

Affected Products

Vendor	Product	Affected Versions	CPE	Subscribe
CESNET	ipfixcol2	2.7.1 ~ 2.9.0	-

II. Public POCs for CVE-2026-122127

#	POC Description	Source Link	Shenlong Link

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No public POC found.

III. Intelligence Information for CVE-2026-122127

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Other References for CVE-2026-122127 (5)

https://github.com/CESNET/ipfixcol2 product
https://github.com/CESNET/ipfixcol2/blob/v2.8.0/src/plugins/input/tcp/src/Lz4Decoder.cpp#L139-L151 technical-description
https://github.com/CESNET/ipfixcol2/commit/fd5cb168efb4b864d33f655174711b2779cef502 patch
https://github.com/CESNET/ipfixcol2/releases/tag/v2.9.0 release-notes
https://www.vulncheck.com/advisories/cesnet-ipfixcol2-2.7.1-before-2.9.0-heap-buffer-overflow-via-tcp-lz4-decoder third-party-advisory

https://www.cve.org/CVERecord?id=CVE-2026-122127

Same Patch Batch · CESNET · 2026-11-04 · 3 CVEs total

CVE-2026-122130	8.2 HIGH	CESNET ipfixcol2 2.3.0 before 2.9.0 Buffer Overflow via Forwarder Output Plugin
CVE-2026-122129	5.3 MEDIUM	CESNET ipfixcol2 2.7.1 before 2.9.0 Memory Exhaustion via TCP LZ4 Decoder

IV. Related Vulnerabilities

Same product: ipfixcol2

Same vendor: CESNET

Same weakness: CWE-787