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CVE-2026-55407— Buffa: Memory Exhaustion Denial of Service in decode_unknown_field via Unbounded Allocation

Quick assessment

Affected
anthropics buffa
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.

Anthropic buffa是美国Anthropic公司的一款代理服务器软件。 Anthropic buffa 0.8.0之前版本存在资源管理错误漏洞，该漏洞源于decode_unknown_field函数分配堆内存与不可信输入成比例，未强制执行分配预算，可能导致未经身份验证的攻击者通过内存耗尽使进程崩溃。

AI Predicted 7.5 Difficulty: Easy EPSS 0.76% · P55

Possible ATT&CK Techniques 1 AI

T1496 · Resource Hijacking

Affected Version Matrix 1

VendorProduct Version RangeStatus
anthropics buffa < 0.8.0 affected
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I. Basic Information for CVE-2026-55407

Vulnerability Information
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Vulnerability Title
Buffa: Memory Exhaustion Denial of Service in decode_unknown_field via Unbounded Allocation
Source: CVE Program / CVE List V5
Vulnerability Description
Buffa is a pure-Rust Protocol Buffers implementation with first-class protobuf editions support. Prior to 0.8.0, the decode_unknown_field function in buffa's protobuf decoder allocated heap memory in proportion to untrusted input (unknown fields in the serialized protobuf) without enforcing an allocation budget, affecting any message decoded from untrusted input using code generated with preserve_unknown_fields=true (the default); a small, well-formed payload of nested unknown fields inside a StartGroup could trigger roughly 22x memory amplification (for example a 64 MiB input forcing about 1.4 GB of heap allocation), and length-delimited unknown fields could be sized arbitrarily, so an unauthenticated attacker could crash a process through memory exhaustion because the top-level message size cap did not account for in-decode amplification. This issue is fixed in version 0.8.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
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
Vulnerability Title
Anthropic buffa 资源管理错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Anthropic buffa是美国Anthropic公司的一款代理服务器软件。 Anthropic buffa 0.8.0之前版本存在资源管理错误漏洞，该漏洞源于decode_unknown_field函数分配堆内存与不可信输入成比例，未强制执行分配预算，可能导致未经身份验证的攻击者通过内存耗尽使进程崩溃。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
anthropics buffa < 0.8.0 -

II. Public POCs for CVE-2026-55407

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III. Intelligence Information for CVE-2026-55407

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Patches & Fixes for CVE-2026-55407 (1)

Vendor Advisories for CVE-2026-55407 (1)

Vendor Pages for CVE-2026-55407 (1)

Same Patch Batch · anthropics · 2026-07-16 · 3 CVEs total

CVE-2026-47751 Claude Code Action: Malicious MCP Server Configuration in PRs Enables Remote Code Executio
CVE-2026-55406 Buffa: Use-After-Free in OwnedView via Unsound 'static Lifetime Promotion in Deref

IV. Related Vulnerabilities

Same product: buffa
Same vendor: anthropics
Same weakness: CWE-400