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CVE-2026-33630— c-ares : Use-after-free / double-free in c-ares query-completion handling, remotely triggerable via ares_getaddrinfo() over TCP

Quick assessment

Affected
c-ares c-ares
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.

c-ares 是一个异步域名解析库。在 1.32.3 版本到 1.34.7 版本之间，c-ares 在查询完成处理中存在使用已释放内存（use-after-free）和重复释放（double-free）漏洞。 该缺陷的根本原因是：当查询的回调函数被调用时，该查询仍然链接在通道的内部查找结构中。这一问题在重传/结束路径的多个位置都存在，包括超时处理、响应处理和查询分发等场景。如果该查询本身，或者在 情况下其所属的 ，作为回调执行的副作用被释放，那么随后该对象会被再次访问和/或再次释放，从而导致内存错误。 此漏洞已在

CVSS 7.5 · High

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 1

VendorProduct Version RangeStatus
c-ares c-ares >= 1.32.3, < 1.34.7 affected
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I. Basic Information for CVE-2026-33630

Vulnerability Information
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Vulnerability Title
c-ares : Use-after-free / double-free in c-ares query-completion handling, remotely triggerable via ares_getaddrinfo() over TCP
Source: CVE Program / CVE List V5
Vulnerability Description
c-ares is an asynchronous resolver library. From ver 1.32.3 until 1.34.7, a use-after-free / double-free in c-ares' query-completion handling. The same flaw — a query's callback being invoked while the query is still linked in the channel's internal lookup structures — is present at multiple points in the resend/finish path (timeout handling, response handling, and query dispatch). If the query, or for ares_getaddrinfo() the owning host_query, is freed as a side effect of that callback, it is then accessed and/or freed a second time. This vulnerability is fixed in ver 1.34.7.
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
双重释放
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
c-ares c-ares >= 1.32.3, < 1.34.7 -

II. Public POCs for CVE-2026-33630

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III. Intelligence Information for CVE-2026-33630

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Patches & Fixes for CVE-2026-33630 (3)

Vendor Advisories for CVE-2026-33630 (1)

Vendor Pages for CVE-2026-33630 (1)

IV. Related Vulnerabilities

Same product: c-ares
Same vendor: c-ares
Same weakness: CWE-415

V. Comments for CVE-2026-33630

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