CVE-2026-55407

MEDIUMPre-NVD 6.36.3
EchelonGraph scoreLOW confidence

This medium-severity CVE scores 6.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: secondary
Trending — 3 sources updated this week
6.3
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
  • Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS: 1%CVSS: 6.3Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
6.3
EG Score
6.3(low)
EG Risk
—
EPSS
43.5%
KEV
Not listed

Published

July 16, 2026

Last Modified

July 16, 2026

Advisory Details (3)

Auto-updated Jul 16, 2026
Patch available. Sources: github_pr, github_release, github.
github_release Patch Available

v0.8.0

Patch available: anthropics/buffa v0.8.0

https://github.com/anthropics/buffa/releases/tag/v0.8.0
github_pr

decode: limit unknown fields to bound memory amplification (owned, dynamic, and view paths)

Fix merged in anthropics/buffa PR #184 on 2026-06-11 — awaiting tagged release

https://github.com/anthropics/buffa/pull/184
github Patch Available

Memory Exhaustion Denial of Service in decode_unknown_field via Unbounded Allocation · Advisory · anthropics/buffa · GitHub

https://github.com/anthropics/buffa/security/advisories/GHSA-f9qc-qg88-7pq5

Weakness Classification(3)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 9× in last 7d / 9× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-22 14:08 UTCEPSS rescore
  2. 2026-07-21 15:25 UTCEPSS rescore
  3. 2026-07-20 17:08 UTCEPSS rescore
  4. 2026-07-19 14:31 UTCEPSS rescore
  5. 2026-07-19 14:31 UTCEPSS rescore
  6. 2026-07-19 02:29 UTCEPSS rescore
  7. 2026-07-18 10:04 UTCEPSS rescore
  8. 2026-07-16 16:29 UTCEG score recompute
  9. 2026-07-16 16:28 UTCMITRE cvelistV5first tracked

Frequently asked(5)

What is CVE-2026-55407?
CVE-2026-55407 is a medium vulnerability published on July 16, 2026. Buffa is a pure-Rust Protocol Buffers implementation with first-class protobuf editions support. Prior to 0.8.0, the decodeunknownfield function in buffa's protobuf decoder allocated heap memory in proportion to untrusted input (unknown fields in the serialized protobuf) without enforcing an…
When was CVE-2026-55407 disclosed?
CVE-2026-55407 was first published in the National Vulnerability Database on July 16, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55407 actively exploited?
CVE-2026-55407 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 43.5% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-55407?
CVE-2026-55407 has a CVSS v3 base score of 6.3 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-55407?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-55407, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

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