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CVE-2026-80212

Quick assessment

Affected
Ruby resolv
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 0.7.2 版本之前的 Ruby 库中发现了一个问题。在解码响应时， 、 和 会为遇到的每一个未知的 DNS 资源记录（类型、类别）对，或每一个未知的 SvcParamKey 动态生成一个新的类。每个生成的类都会永久注册为 （或 ）上的常量，并且作为类查找哈希表（ClassHash）中的一个条目，因此即使在响应被丢弃之后，这些类仍然通过该常量保持可达状态。由于类型和类别各为 16 位值，攻击者若控制 DNS 响应（例如伪造的响应，或恶意/被劫持的上游 DNS 服务器），则可以在大约 2^32 个不同的（类型，类

CVSS 7.5 · High

Affected Version Matrix 2

VendorProduct Version RangeStatus
Ruby resolv < 0.3.2 affected
0.4.0< 0.7.2 affected
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I. Basic Information for CVE-2026-80212

Vulnerability Information
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Vulnerability Title
N/A
Source: CVE Program / CVE List V5
Vulnerability Description
An issue was discovered in the resolv gem before 0.7.2 for Ruby. Resolv::DNS::Resource.get_class, Resolv::DNS::Resource::Generic.create, and Resolv::DNS::SvcParam::Generic.create generate a new class for each unknown DNS resource record (type, class) pair, or each unknown SvcParamKey, encountered while decoding a response. Each generated class was permanently registered both as a constant on Resource (or SvcParam::Generic) and as an entry in a class-lookup hash (ClassHash), and thus the class remained reachable through that constant after the response was discarded. Type and class are each 16-bit values, and thus an attacker controlling DNS responses (a spoofed response, or a malicious or hijacked upstream DNS server) has roughly 2^32 distinct (type, class) pairs to choose from. A single response of a few hundred kilobytes carrying tens of thousands of distinct unknown types permanently grows process memory by tens of megabytes; repeated responses accumulate without bound and are never reclaimed by garbage collection, because the constant keeps each class alive. Any code path that calls Resolv::DNS::Message.decode on attacker-influenced DNS responses is affected. resolv is a default gem, and thus this is reachable from a plain Ruby installation without any additional dependency.
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
不加限制或调节的资源分配
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Ruby resolv 0 ~ 0.3.2 -

II. Public POCs for CVE-2026-80212

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III. Intelligence Information for CVE-2026-80212

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Vendor Advisories for CVE-2026-80212 (1)

Proof of Concept for CVE-2026-80212 (1)

IV. Related Vulnerabilities

Same product: resolv
Same vendor: Ruby
Same weakness: CWE-770

V. Comments for CVE-2026-80212

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