CVE-2026-123202— libnxml before 0.18.6 Stack-based Buffer Overflow via long multi-byte XML name

Quick assessment

Affected

bakulf libnxml

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.

libnxml 0.18.6 之前的版本在 src/nxml_parser.c 中存在一个基于栈的缓冲区溢出漏洞。远程攻击者可通过提供包含超长 XML 名称的输入，向一个 1024 字节的栈缓冲区写入超出其边界的数据。攻击者可构造包含 1022 个字符的 XML 或 RSS 元素、属性、DOCTYPE 或实体名称，并在其末尾附加一个多字节 UTF-8 字符，从而导致解析应用程序崩溃。

CVSS 7.5 · High Updated Nov 06, 2026

Possible ATT&CK Techniques 2 AI

T1068 · Exploitation for Privilege Escalation T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

Vendor	Product	Version Range	Status
bakulf	libnxml	`< 0.18.6`	affected

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Vulnerability Information

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Vulnerability Title

libnxml before 0.18.6 Stack-based Buffer Overflow via long multi-byte XML name

Source: CVE Program / CVE List V5

Vulnerability Description

libnxml before 0.18.6 contains a stack-based buffer overflow vulnerability in src/nxml_parser.c that allows remote attackers to write past a 1024-byte stack buffer via long XML names. Attackers can supply XML or RSS feeds with a 1022-character element, attribute, DOCTYPE or entity name ending in a multi-byte UTF-8 character to crash parsing applications.

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

栈缓冲区溢出

Source: CVE Program / CVE List V5

Affected Products

Vendor	Product	Affected Versions	CPE	Subscribe
bakulf	libnxml	0 ~ 0.18.6	-

II. Public POCs for CVE-2026-123202

#	POC Description	Source Link	Shenlong Link

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No public POC found.

III. Intelligence Information for CVE-2026-123202

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Other References for CVE-2026-123202 (4)

https://github.com/bakulf/libnxml/commit/fbac242374883edf2ec14127ca6d2accf4704b6a patch
https://github.com/bakulf/libnxml/blob/9272d1cd6fee88fe7fd4fd812736d95a6ba25f2f/src/nxml_parser.c#L952-L958 technical-description
https://github.com/bakulf/libnxml/releases/tag/0.18.6 release-notes
https://www.vulncheck.com/advisories/libnxml-before-0.18.6-stack-based-buffer-overflow-via-long-multi-byte-xml-name third-party-advisory

https://www.cve.org/CVERecord?id=CVE-2026-123202

IV. Related Vulnerabilities

Same weakness: CWE-121