CVE-2026-49982— tmp: Type-confusion bypass of _assertPath in tmp@0.2.6 allows path traversal via non-string prefix/postfix/template

tmp: Type-confusion bypass of _assertPath in tmp@0.2.6 allows path traversal via non-string prefix/postfix/template

tmp is a temporary file and directory creator for node.js. In version 0.2.6, the _assertPath guard added to tmp rejects only string values that contain the substring ... It is bypassed when prefix, postfix, or template is supplied as a non-string value (Array, Buffer, or any object) whose includes('..') returns falsy but whose stringification still contains ../. The value flows through Array.prototype.join/String coercion inside _generateTmpName and path.join(tmpDir, opts.dir, name), producing a final path that escapes tmpdir and creates a file or directory at an attacker-controlled location with the host process's privileges. This affects any application that forwards untrusted request data (a common pattern is JSON body fields or qs-parsed bracket-array query strings such as ?prefix[]=...) into tmp.file, tmp.fileSync, tmp.dir, tmp.dirSync, tmp.tmpName, or tmp.tmpNameSync without explicit type coercion. This vulnerability is fixed in 0.2.7.

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

输入验证不恰当

tmp 输入验证错误漏洞

tmp是KARASZI István个人开发者的一个node.js的临时文件和目录创建器。 tmp 0.2.6版本存在输入验证错误漏洞，该漏洞源于_assertPath守卫仅拒绝包含子字符串..的字符串值，当prefix、postfix或template作为非字符串值提供时，其includes( .. )返回假值但字符串化后仍包含../，导致路径遍历。攻击者可利用此漏洞在主机进程权限下在攻击者控制的位置创建文件或目录。

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