CVE-2026-121944— sngrep through 1.9.0 Infinite Loop DoS via Crafted NFLOG TLV

Quick assessment

Affected

irontec sngrep

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.

sngrep 1.9.0 及以下版本在 src/capture.c 中的 capture_packet_reasm_ip() 函数存在无限循环漏洞。攻击者可利用精心构造的 NFLOG TLV（类型 - 长度 - 值）触发该漏洞，导致拒绝服务（DoS）。具体而言，攻击者可提供一个链路类型为 NFLOG 的 pcap 文件，其中包含一个长度小于 4 字节的非载荷（non-payload）TLV，致使捕获线程以 100% CPU 占用率持续空转，从而停止处理后续数据包。

CVSS 5.5 · Medium Updated Nov 05, 2026

Possible ATT&CK Techniques 1 AI

T1499.002 · Service Exhaustion Flood

Affected Version Matrix 1

Vendor	Product	Version Range	Status
irontec	sngrep	`≤ 1.9.0`	affected

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Vulnerability Information

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Vulnerability Title

sngrep through 1.9.0 Infinite Loop DoS via Crafted NFLOG TLV

Source: CVE Program / CVE List V5

Vulnerability Description

sngrep through 1.9.0 contains an infinite loop vulnerability in capture_packet_reasm_ip() in src/capture.c that allows attackers to cause denial of service via crafted NFLOG TLVs. Attackers can supply a pcap file with link type NFLOG containing a non-payload TLV with length under 4, making the capture thread spin at full CPU and stop processing packets.

Source: CVE Program / CVE List V5

CVSS Information

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

Source: CVE Program / CVE List V5

Vulnerability Type

不可达退出条件的循环(无限循环)

Source: CVE Program / CVE List V5

Affected Products

Vendor	Product	Affected Versions	CPE	Subscribe
irontec	sngrep	0 ~ 1.9.0	-

II. Public POCs for CVE-2026-121944

#	POC Description	Source Link	Shenlong Link

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III. Intelligence Information for CVE-2026-121944

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Other References for CVE-2026-121944 (4)

https://github.com/irontec/sngrep/issues/589 issue-tracking
https://hackmd.io/@haindpwn/sngrep-sip-payload-missing-nul-oob-read third-party-advisory
https://github.com/irontec/sngrep/blob/v1.9.0/src/capture.c#L581-L598 technical-description
https://www.vulncheck.com/advisories/sngrep-through-1.9.0-infinite-loop-dos-via-crafted-nflog-tlv third-party-advisory

https://www.cve.org/CVERecord?id=CVE-2026-121944

IV. Related Vulnerabilities

Same product: sngrep

Same vendor: irontec

Same weakness: CWE-835