Resource exhaustion in Protobufjs Protobuf.js
CVE-2026-54270
protobufjs compiles protobuf definitions into JavaScript (JS) functions. From 8.2.0 to 8.4.2, protobufjs preserved unknown wire elements in message.$unknowns and did not provide a decode-time option to discard unknown fields before retaining them. A crafted protobuf payload containing many unknown fields could therefore cause a decoded message to retain substantially more memory than the input size would suggest, even when unknown-field round-tripping is not needed. protobufjs 8.5.0 added the relevant decode-time options, allowing applications that decode untrusted protobuf data to disable unknown-field retention during decode. protobufjs 8.6.2 flips the default so unknown fields are discarded unless explicitly opted into.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.3 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L.
EPSS exploit prediction
EPSS: 0.004 (31.9th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 32nd percentile — 31.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: 0.000
Affected products
- Protobufjs Protobuf.js — versions >=8.2.0, < 8.5.0
- Protobufjs Project
Weakness classification (CWE)
References
- github.com/protobufjs/protobuf.js/security/advisories/GHSA-94rc-8x27-4472 (Mitigation, Vendor Advisory)
Frequently asked questions
- What is CVE-2026-54270?
- CVE-2026-54270 is a medium-severity vulnerability in Protobufjs Protobuf.js, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 5.3/10. Published 2026-06-22.
- How severe is CVE-2026-54270?
- Medium severity. CVSS v3 base score is 5.3 out of 10.