anthropics buffa up to 0.7.x Decoder decode_unknown_field allocation of resources

Summaryinfo

A vulnerability, which was classified as problematic, has been found in anthropics buffa up to 0.7.x. The affected element is the function decode_unknown_field of the component Decoder. The manipulation leads to allocation of resources. This vulnerability is listed as CVE-2026-55407. The attack may be initiated remotely. There is no available exploit.

Detailsinfo

A vulnerability was found in anthropics buffa up to 0.7.x. It has been rated as problematic. This issue affects the function decode_unknown_field of the component Decoder. The manipulation with an unknown input leads to a allocation of resources vulnerability. Using CWE to declare the problem leads to CWE-770. The product allocates a reusable resource or group of resources on behalf of an actor without imposing any restrictions on the size or number of resources that can be allocated, in violation of the intended security policy for that actor. Impacted is availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2026-55407 since 06/16/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1499 according to MITRE ATT&CK.

Upgrading to version 0.8.0 eliminates this vulnerability.

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Productinfo

Type

• Artificial Intelligence Software

Vendor

• anthropics

Name

• buffa

Version

• 0.1
• 0.2
• 0.3
• 0.4
• 0.5
• 0.6
• 0.7

Website

• Product: https://github.com/anthropics/buffa/

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