Vulnerability-Lookup

CVE-2026-55407 (GCVE-0-2026-55407)

Vulnerability from cvelistv5 – Published: 2026-07-16 15:57 – Updated: 2026-07-16 18:04

Title

Buffa: Memory Exhaustion Denial of Service in decode_unknown_field via Unbounded Allocation

Summary

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.

Severity

6.3 (Medium)


                        
                          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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-07-16 18:03 UTC

CWE

CWE-400 - Uncontrolled Resource Consumption
CWE-770 - Allocation of Resources Without Limits or Throttling
CWE-789 - Memory Allocation with Excessive Size Value

Assigner

GitHub_M CNA under the mitre root

CNA scorecard C 72/100 over 7831 records in the last 180 days details

References

4 references

URL	Tags
https://github.com/anthropics/buffa/security/advi…	x_refsource_CONFIRM
https://github.com/anthropics/buffa/pull/184	x_refsource_MISC
https://github.com/anthropics/buffa/commit/278fa4…	x_refsource_MISC
https://github.com/anthropics/buffa/releases/tag/v0.8.0	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
anthropics	buffa	Affected: < 0.8.0	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-55407

Vulnerability from fkie_nvd - Published: 2026-07-16 17:16 - Updated: 2026-10-24 20:10

Severity

6.3 (Medium) - 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

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/anthropics/buffa/commit/278fa43fcff661d4ee6bd83b75955a153d4281fc
	security-advisories@github.com	https://github.com/anthropics/buffa/pull/184
	security-advisories@github.com	https://github.com/anthropics/buffa/releases/tag/v0.8.0
	security-advisories@github.com	https://github.com/anthropics/buffa/security/advisories/GHSA-f9qc-qg88-7pq5

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "buffa",
          "vendor": "anthropics",
          "versions": [
            {
              "status": "affected",
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    },
    {
      "lang": "es",
      "value": "Buffa es una implementaci\u00f3n pura en Rust de Protocol Buffers con soporte de primera clase para ediciones de protobuf. Antes de la versi\u00f3n 0.8.0, la funci\u00f3n \u201cdecode_unknown_field\u201d en el decodificador de protobuf de Buffa asignaba memoria del mont\u00f3n en proporci\u00f3n a la entrada no confiable (campos desconocidos en el protobuf serializado) sin aplicar un presupuesto de asignaci\u00f3n, afectando cualquier mensaje decodificado de entrada no confiable usando c\u00f3digo generado con \u201cpreserve_unknown_fields=true\u201d (el valor predeterminado); una carga \u00fatil peque\u00f1a y bien formada de campos desconocidos anidados dentro de un \u201cStartGroup\u201d podr\u00eda desencadenar aproximadamente una amplificaci\u00f3n de memoria de 22x (por ejemplo, una entrada de 64 MiB forzando aproximadamente 1.4 GB de asignaci\u00f3n de memoria del mont\u00f3n), y los campos desconocidos delimitados por longitud podr\u00edan tener un tama\u00f1o arbitrario, por lo que un atacante no autenticado podr\u00eda bloquear un proceso por agotamiento de memoria porque el l\u00edmite de tama\u00f1o del mensaje de nivel superior no ten\u00eda en cuenta la amplificaci\u00f3n durante la decodificaci\u00f3n. Este problema est\u00e1 solucionado en la versi\u00f3n 0.8.0."
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  "lastModified": "2026-10-24T20:10:00.137",
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      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 6.3,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "NONE",
          "subIntegrityImpact": "NONE",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "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/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",
          "version": "4.0",
          "vulnAvailabilityImpact": "LOW",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "NONE",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "security-advisories@github.com",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-55407",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-07-16T18:03:55.427453Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-07-16T17:16:57.770",
  "references": [
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/anthropics/buffa/commit/278fa43fcff661d4ee6bd83b75955a153d4281fc"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/anthropics/buffa/pull/184"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/anthropics/buffa/releases/tag/v0.8.0"
    },
    {
      "source": "security-advisories@github.com",
      "url": "https://github.com/anthropics/buffa/security/advisories/GHSA-f9qc-qg88-7pq5"
    }
  ],
  "sourceIdentifier": "security-advisories@github.com",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-400"
        },
        {
          "lang": "en",
          "value": "CWE-770"
        },
        {
          "lang": "en",
          "value": "CWE-789"
        }
      ],
      "source": "security-advisories@github.com",
      "type": "Secondary"
    }
  ]
}

GHSA-F9QC-QG88-7PQ5

Vulnerability from github – Published: 2026-08-28 18:34 – Updated: 2026-08-28 18:34

Summary

Buffa Vulnerable to Memory Exhaustion Denial of Service in decode_unknown_field via Unbounded Allocation

Details

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. Any message decoded from untrusted input using code generated with preserve_unknown_fields=true (the default) was affected. A small, well-formed payload of nested unknown fields inside a StartGroup could trigger roughly 22× memory amplification (e.g., a 64 MiB input forcing ~1.4 GB of heap allocation), and length-delimited unknown fields could be sized arbitrarily, enabling an unauthenticated attacker to crash a process via memory exhaustion. This was reachable from the default decode APIs, since the top-level message size cap did not account for in-decode amplification.

For users of connectrpc - the DEFAULT_MAX_MESSAGE_SIZE for connectrpc is 4MiB, which limits amplification in the worst case to ~88 MiB of memory. A flood of concurrent requests with this pattern could still be used to exhaust available memory, however.

Users are advised to either set preserve_unknown_fields=false on their current generated code, or upgrade to 0.8.0, which enforces per-message unknown field count limits - this is configurable, with a default of 1 million unknown fields, or ~40MiB of allocation overhead per message. Users are advised to update to the latest version, which enforces per-message unknown field count limits.

Thank you to @p80n-sec for reporting this issue.

Severity

6.3 (Medium)


                  
                    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

Show details on source website

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To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "crates.io",
        "name": "buffa"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.8.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-55407"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400",
      "CWE-770",
      "CWE-789"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-08-28T18:34:22Z",
    "nvd_published_at": "2026-07-16T17:16:57Z",
    "severity": "MODERATE"
  },
  "details": "The `decode_unknown_field` function in buffa\u0027s protobuf decoder allocated heap memory in proportion to untrusted input (unknown fields in the serialized protobuf) without enforcing an allocation budget. Any message decoded from untrusted input using code generated with `preserve_unknown_fields=true` (the default) was affected. A small, well-formed payload of nested unknown fields inside a StartGroup could trigger roughly 22\u00d7 memory amplification (e.g., a 64 MiB input forcing ~1.4 GB of heap allocation), and length-delimited unknown fields could be sized arbitrarily, enabling an unauthenticated attacker to crash a process via memory exhaustion. This was reachable from the default decode APIs, since the top-level message size cap did not account for in-decode amplification. \n\nFor users of connectrpc - the DEFAULT_MAX_MESSAGE_SIZE for connectrpc is 4MiB, which limits amplification in the worst case to ~88 MiB of memory. A flood of concurrent requests with this pattern could still be used to exhaust available memory, however.\n\nUsers are advised to either set `preserve_unknown_fields=false` on their current generated code, or upgrade to 0.8.0, which enforces per-message unknown field count limits - this is configurable, with a default of 1 million unknown fields, or ~40MiB of allocation overhead per message.\nUsers are advised to update to the latest version, which enforces per-message unknown field count limits.\n\nThank you to @p80n-sec for reporting this issue.",
  "id": "GHSA-f9qc-qg88-7pq5",
  "modified": "2026-08-28T18:34:22Z",
  "published": "2026-08-28T18:34:22Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/anthropics/buffa/security/advisories/GHSA-f9qc-qg88-7pq5"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-55407"
    },
    {
      "type": "WEB",
      "url": "https://github.com/anthropics/buffa/pull/184"
    },
    {
      "type": "WEB",
      "url": "https://github.com/anthropics/buffa/commit/278fa43fcff661d4ee6bd83b75955a153d4281fc"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/anthropics/buffa"
    },
    {
      "type": "WEB",
      "url": "https://github.com/anthropics/buffa/releases/tag/v0.8.0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Buffa Vulnerable to Memory Exhaustion Denial of Service in decode_unknown_field via Unbounded Allocation"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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Following the VTEM framework (Black Hat USA 2015), time to patch starts when the vendor or a coordinator was informed, total time to patch at discovery, and disclosure to patch at public disclosure; vendor response time runs from the report to its acknowledgement. Time to exploit and time unpatched start at the earliest discovery or report, falling back to public disclosure. Unpatched time ends at the first recorded patch, or the calculation time when no patch is recorded. Exploitation to patch shows the interval between those two events; a published proof of concept is a public exploit, not exploitation.

Each result shows its source dates. A negative interval means the end event came first; when date-only inputs leave the order open, the result says so. Date-only inputs are approximate. The earliest evidence wins: KEV report dates and sightings are labelled as such. Records describing another vulnerability are listed but never calculated from, and a PoC alone does not establish exploitation. Missing patch evidence does not prove that no patch exists. Filters below change the event list only.

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CVE-2026-55407 (GCVE-0-2026-55407)

FKIE_CVE-2026-55407

GHSA-F9QC-QG88-7PQ5

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