CVE-2026-55407
Buffa: Memory Exhaustion Denial of Service in decode_unknown_field via Unbounded Allocation
- Published
- Updated
- Reserved
- Assigned by
- GitHub_M
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.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| GitHub_MCNA (assigner) | 4.0 | Medium6.3 | 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 |
| NVDNVD · Deferred | 4.0 | Medium6.3 | 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 |
- EPSS (exploitation in 30 days)
- 0.76% · top 45% of all CVEs (6 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: partial
The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.3.
Weakness
- CWE-400: Uncontrolled Resource Consumption (opens in a new tab)All about CWE-400 and its CVEs
- CWE-770: Allocation of Resources Without Limits or Throttling (opens in a new tab)All about CWE-770 and its CVEs
- CWE-789: Memory Allocation with Excessive Size Value (opens in a new tab)All about CWE-789 and its CVEs
Affected products
- affected < 0.8.0
Affected packages
From reviewed advisories of the GitHub Advisory Database.
- crates.iobuffaGHSA-f9qc-qg88-7pq5 (opens in a new tab)
References (4)
- https://github.com/anthropics/buffa/security/advisories/GHSA-f9qc-qg88-7pq5 (opens in a new tab)x_refsource_CONFIRM
- https://github.com/anthropics/buffa/pull/184 (opens in a new tab)x_refsource_MISC
- https://github.com/anthropics/buffa/commit/278fa43fcff661d4ee6bd83b75955a153d4281fc (opens in a new tab)x_refsource_MISC
- https://github.com/anthropics/buffa/releases/tag/v0.8.0 (opens in a new tab)x_refsource_MISC
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisory GHSA-f9qc-qg88-7pq5 (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://trackcve.app/cve/CVE-2026-55407)Record last updated .