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CVE-2026-19542— Stack-based out-of-bounds write in tdelete during tree rebalancing

Quick assessment

Affected
The GNU C Library glibc
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 GNU C Library（glibc）版本 2.1 至 2.44 中，在对足够深的树结构调用 时，可能会在栈上通过 分配的数组末尾之外写入一个指针，从而导致应用程序崩溃。 的实现维护一个显式的父节点栈用于再平衡，该栈在向下遍历树时按需扩展。其中两个再平衡分支在推入额外条目时未检查容量，当栈恰好满时会导致越界写入。触发此问题要求存在一个深度恰好为 40（或 40 加上 20 的倍数）的节点，这意味着树至少包含一百万个节点。因此，攻击者必须通过一个使用 和 的应用程序，驱动大量插入和删除操作。被写入的值是指向树节

CVSS 5.6 · Medium

Affected Version Matrix 1

VendorProduct Version RangeStatus
The GNU C Library glibc 2.1≤ 2.44 affected
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I. Basic Information for CVE-2026-19542

Vulnerability Information
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Vulnerability Title
Stack-based out-of-bounds write in tdelete during tree rebalancing
Source: CVE Program / CVE List V5
Vulnerability Description
Calling tdelete on a sufficiently deep tree in the GNU C Library version 2.1 to 2.44 may write one pointer past the end of an alloca-allocated array on the stack, which may crash the application. The tdelete implementation keeps an explicit stack of parent nodes for rebalancing, which is grown as needed while descending the tree. Two rebalancing branches push an additional entry without checking the capacity, and write past the array when the stack is exactly full. Triggering this requires a node at a depth of exactly 40 (or 40 plus a multiple of 20), which implies a tree with at least a million nodes, so an attacker must drive a large number of insertions and deletions through an application that uses tsearch and tdelete. The written value is a pointer into a tree node and is not directly attacker controlled. No affected application in common distributions has been identified.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:L
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
The GNU C Library glibc 2.1 ~ 2.44 -

II. Public POCs for CVE-2026-19542

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III. Intelligence Information for CVE-2026-19542

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Vendor Advisories for CVE-2026-19542 (1)

Other References for CVE-2026-19542 (1)

IV. Related Vulnerabilities

Same product: glibc
Same vendor: The GNU C Library
Same weakness: CWE-121

V. Comments for CVE-2026-19542

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