CVE-2026-69186— c-ares: Memory-amplification denial of service via unvalidated DNS header record counts
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 is an asynchronous resolver library. Prior to 1.34.7, ares_dns_parse() trusts the attacker-controlled ANCOUNT, NSCOUNT, and ARCOUNT fields before confirming that the DNS response contains enough bytes for the claimed records. Because process_answer() in
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I. Basic Information for CVE-2026-69186
Vulnerability Information
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Vulnerability Title
c-ares: Memory-amplification denial of service via unvalidated DNS header record counts
Source: CVE Program / CVE List V5
Vulnerability Description
c-ares is an asynchronous resolver library. Prior to 1.34.7, ares_dns_parse() trusts the attacker-controlled ANCOUNT, NSCOUNT, and ARCOUNT fields before confirming that the DNS response contains enough bytes for the claimed records. Because process_answer() invokes parsing before transaction ID and question validation, a malicious DNS response can cause ares_dns_record_rr_prealloc() and ares_array_set_size() to reserve disproportionate heap memory for a tiny message. Repeated responses create large allocation and release cycles that can degrade or deny name resolution, without causing memory corruption or information disclosure. This issue is fixed in version 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:L
Source: CVE Program / CVE List V5
Vulnerability Type
未加控制的资源消耗(资源穷尽)
Source: CVE Program / CVE List V5
Affected Products
II. Public POCs for CVE-2026-69186
| # | POC Description | Source Link | Shenlong Link |
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Patches & Fixes for CVE-2026-69186 (3)
Vendor Pages for CVE-2026-69186 (1)
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🔗 Release 1.34.7 · c-ares/c-ares · GitHub x_refsource_MISC
Other References for CVE-2026-69186 (1)
IV. Related Vulnerabilities
Same product: c-ares
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CVE-2026-69184
c-ares: CPU-exhaustion denial of service via unbounded DNS n -
CVE-2026-33630
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CVE-2025-62408
c-ares has a Use After Free vulnerability when connection is -
CVE-2025-31498
c-ares has a use-after-free in read_answers() -
CVE-2024-25629
c-ares out of bounds read in ares__read_line()
Same vendor: c-ares
-
CVE-2026-69184
c-ares: CPU-exhaustion denial of service via unbounded DNS n -
CVE-2026-33630
c-ares : Use-after-free / double-free in c-ares query-comple -
CVE-2025-62408
c-ares has a Use After Free vulnerability when connection is -
CVE-2025-31498
c-ares has a use-after-free in read_answers() -
CVE-2024-25629
c-ares out of bounds read in ares__read_line()
Same weakness: CWE-400
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CVE-2026-33625
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CVE-2026-68523
Fulgur: Unbounded page slicing from attacker-controlled CSS
V. Comments for CVE-2026-69186
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