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CVE-2026-89092— Stack overflow in nscd due to unbounded alloca use

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.

自 GNU C 库 2.3.4 起，nscd 服务可能在恶意 DNS 服务器返回过大的 DNS 查询响应时，因栈溢出（stack overflow）而导致崩溃，从而导致系统的 DNS 解析性能下降。 利用此漏洞需要系统启用 nscd 服务，并使用不受信任的 DNS 服务器进行域名解析，且该受控 DNS 服务器能够处理足够大的记录，从而在 nscd 线程栈中引发栈溢出。在实验过程中，BIND 9 无法处理大记录，但未来版本或其他名称服务器可能会改变这一情况。在典型安装中，nscd 作为独立用户运行在隔离的环境中，且无

CVSS 4.2 · Medium EPSS 0.24% · P15

Possible ATT&CK Techniques 1 AI

T1210 · Exploitation of Remote Services

Affected Version Matrix 1

VendorProduct Version RangeStatus
The GNU C Library glibc 2.3.4< 2.45 affected
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I. Basic Information for CVE-2026-89092

Vulnerability Information
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Vulnerability Title
Stack overflow in nscd due to unbounded alloca use
Source: CVE Program / CVE List V5
Vulnerability Description
The nscd service in the GNU C Library 2.3.4 onwards may crash due to a stack overflow when a malicious DNS server returns too large a response for a DNS query, resulting in degraded DNS resolution for the system. Exploitation of this bug needs a system that has nscd enabled and using an untrusted DNS server for name resolution, with the compromised DNS server being capable of processing records large enough to result in a stack overflow in an nscd thread stack.  During experimentation, bind 9 was unable to handle large records, but that could change in future or with a different name server.  In typical installations, nscd is executed in an isolated context as its own user without a shell, due to which any compromise of that service is isolated. There is a remote possibility of nscd cache corruption if an attacker manages to get the stack pointer into a desired point in the heap, potentially resulting in other caches in nscd being overwritten with corrupt data through the stack overflow, until the buggy code path eventually results in a crash. Finally, a crash in nscd may result in performance degradation when resolving names, but it does not result in a denial of service.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:L
Source: CVE Program / CVE List V5
Vulnerability Type
未经控制的内存分配
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
The GNU C Library glibc 2.3.4 ~ 2.45 -

II. Public POCs for CVE-2026-89092

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III. Intelligence Information for CVE-2026-89092

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Vendor Advisories for CVE-2026-89092 (1)

Other References for CVE-2026-89092 (1)

IV. Related Vulnerabilities

Same product: glibc
Same vendor: The GNU C Library
Same weakness: CWE-789

V. Comments for CVE-2026-89092

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