CVE-2026-55407
Buffa: Memory Exhaustion Denial of Service in decode_unknown_field via Unbounded Allocation
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.
INFO
Published Date :
July 16, 2026, 5:16 p.m.
Last Modified :
Oct. 24, 2026, 8:10 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-55407
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 4.0 | MEDIUM | [email protected] |
Solution
- Update Buffa to version 0.8.0 or later.
- Ensure proper allocation limits are enforced.
Public PoC/Exploit Available at Github
CVE-2026-55407 has a 2 public
PoC/Exploit available at Github.
Go to the Public Exploits tab to see the list.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-55407.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-55407 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-55407
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
A curated timeline of real AI agent security incidents, breaches, and vulnerabilities (2024-2026). Every entry sourced and dated.
ai-agent-security ai-agents ai-security awesome-list cybersecurity llm-security mcp-security prompt-injection supply-chain-security adversarial-attacks agent-security agentic-ai ai-attacks ai-safety cve incident-response owasp red-team security-research vulnerability
A collection of Vulnerability Research and Reverse Engineering writeups.
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-55407 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-55407 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Translated by [email protected]
Oct. 24, 2026
Action Type Old Value New Value Added Translation Title: buffa de anthropics, Description: Buffa es una implementación pura en Rust de Protocol Buffers con soporte de primera clase para ediciones de protobuf. Antes de la versión 0.8.0, la función “decode_unknown_field” en el decodificador de protobuf de Buffa asignaba memoria del montón en proporción a la entrada no confiable (campos desconocidos en el protobuf serializado) sin aplicar un presupuesto de asignación, afectando cualquier mensaje decodificado de entrada no confiable usando código generado con “preserve_unknown_fields=true” (el valor predeterminado); una carga útil pequeña y bien formada de campos desconocidos anidados dentro de un “StartGroup” podría desencadenar aproximadamente una amplificación de memoria de 22x (por ejemplo, una entrada de 64 MiB forzando aproximadamente 1.4 GB de asignación de memoria del montón), y los campos desconocidos delimitados por longitud podrían tener un tamaño arbitrario, por lo que un atacante no autenticado podría bloquear un proceso por agotamiento de memoria porque el límite de tamaño del mensaje de nivel superior no tenía en cuenta la amplificación durante la decodificación. Este problema está solucionado en la versión 0.8.0. -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jul. 16, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-55407', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-07-16T18:03:55.427453Z'} -
New CVE Received by [email protected]
Jul. 16, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'anthropics', 'product': 'buffa', 'versions': [{'status': 'affected', 'version': '< 0.8.0'}]}] Added 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. Added CVSS V4.0 AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-400 Added CWE CWE-770 Added CWE CWE-789 Added Reference https://github.com/anthropics/buffa/commit/278fa43fcff661d4ee6bd83b75955a153d4281fc Added Reference https://github.com/anthropics/buffa/pull/184 Added Reference https://github.com/anthropics/buffa/releases/tag/v0.8.0 Added Reference https://github.com/anthropics/buffa/security/advisories/GHSA-f9qc-qg88-7pq5