CVE-2026-55407: CWE-400: Uncontrolled Resource Consumption in anthropics buffa
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.
AI Analysis
Technical Summary
CVE-2026-55407 describes an uncontrolled resource consumption vulnerability in the buffa protobuf decoder before version 0.8.0. The decode_unknown_field function allocated heap memory proportional to untrusted input without enforcing limits, especially when decoding unknown fields with preserve_unknown_fields=true (default). Nested unknown fields inside a StartGroup could cause approximately 22x memory amplification, e.g., a 64 MiB input could trigger about 1.4 GB of heap allocation. Length-delimited unknown fields could be arbitrarily large, enabling an unauthenticated attacker to exhaust memory and crash the process. The vulnerability is resolved in buffa version 0.8.0.
Potential Impact
An unauthenticated attacker can supply crafted protobuf messages with unknown fields that cause excessive heap memory allocation during decoding. This can lead to memory exhaustion and process crashes, resulting in denial of service. The amplification effect means relatively small inputs can cause large memory usage spikes.
Mitigation Recommendations
Upgrade buffa to version 0.8.0 or later, where this vulnerability is fixed. No other official remediation or temporary fixes are documented. Patch status is not explicitly stated but the fix is included in version 0.8.0, so upgrading to this version or newer is recommended.
CVE-2026-55407: CWE-400: Uncontrolled Resource Consumption in anthropics buffa
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.
CVSS v4.0
Score 6.3medium
Affected software
pkg:cargo/github/anthropics/buffaRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-55407 describes an uncontrolled resource consumption vulnerability in the buffa protobuf decoder before version 0.8.0. The decode_unknown_field function allocated heap memory proportional to untrusted input without enforcing limits, especially when decoding unknown fields with preserve_unknown_fields=true (default). Nested unknown fields inside a StartGroup could cause approximately 22x memory amplification, e.g., a 64 MiB input could trigger about 1.4 GB of heap allocation. Length-delimited unknown fields could be arbitrarily large, enabling an unauthenticated attacker to exhaust memory and crash the process. The vulnerability is resolved in buffa version 0.8.0.
Potential Impact
An unauthenticated attacker can supply crafted protobuf messages with unknown fields that cause excessive heap memory allocation during decoding. This can lead to memory exhaustion and process crashes, resulting in denial of service. The amplification effect means relatively small inputs can cause large memory usage spikes.
Mitigation Recommendations
Upgrade buffa to version 0.8.0 or later, where this vulnerability is fixed. No other official remediation or temporary fixes are documented. Patch status is not explicitly stated but the fix is included in version 0.8.0, so upgrading to this version or newer is recommended.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-06-16T21:48:43.124Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a5907ce68715ace4356ca82
Added to database: 07/16/2026, 16:33:18 UTC
Last enriched: 07/16/2026, 16:48:36 UTC
Last updated: 07/16/2026, 19:43:18 UTC
Views: 7
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