msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the streaming decoder recursively invokes itself for each complete MessagePack value remaining in a chunk. A remote peer can send one chunk containing many small valid values, causing recursion proportional to the value count, exhausting the JavaScript call stack, and interrupting the process or stream. This issue is fixed in version 6.1.0.
CVE-2026-107300
HIGHPre-NVD 7.57.5—Trending — 3 sources updated this week
EchelonGraph scoreMEDIUM confidence
This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4% (34th percentile of EPSS-scored CVEs). 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: epss, secondary
7.5EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 7.5Exploit: None knownExposed services: Not assessed
A fix is available — apply it.
- CVSS v3
- 7.5
- EG Score
- 7.5HIGHmedium confidence
- EG Risk
- 49EG Risk 49/100CISA SSVC
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity75% × 45%Exploitation0% × 40%Automatability100% × 15%CISA SSVC: Track at low or medium mission impact; Attend at high (mission-essential systems).Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high. - EPSS PROB
- 0.4%
- EPSS %ILE
- 34th
- KEV
- Not listed
CISA SSVCTrack at low or medium mission impact; Attend at high (mission-essential systems).
A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
Exploitation none (CISA Vulnrichment) · Automatable yes (CISA Vulnrichment) · Technical impact partial (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table
Published
October 8, 2026
Last Modified
October 8, 2026
Advisory Details (3)
Auto-updated Oct 8, 2026Patch available. Sources: github_commit, github_release, github.
githubMentions a patch (unverified)
Many buffered values can exhaust the streaming decoder stack · Advisory · mcollina/msgpack5 · GitHub
https://github.com/mcollina/msgpack5/security/advisories/GHSA-5x5g-h9x8-2fh9github_release Patch Available
v6.1.0
Patch available: mcollina/msgpack5 v6.1.0
https://github.com/mcollina/msgpack5/releases/tag/v6.1.0github_commit Patch Available
commit 77fbef144d05 (mcollina/msgpack5)
Patch available: mcollina/msgpack5 v6.1.0 (contains commit 77fbef144d05)
https://github.com/mcollina/msgpack5/commit/77fbef144d05def5d16fc22c37caa64c0a7efebaVendor Advisories for CVE-2026-107300(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(1 across 1 ecosystem)
npm(1)
| Package | Vulnerable range | Fix by version range | Dependents |
|---|---|---|---|
| msgpack5 | — |
| — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 7× in last 7d / 7× 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.
- 2026-10-09 21:58 UTCEG score recompute
- 2026-10-09 20:06 UTCEPSS rescore
- 2026-10-08 18:36 UTCEG score recompute
- 2026-10-08 17:59 UTCEG score recompute
- 2026-10-08 17:25 UTCEG score recompute
- 2026-10-08 17:15 UTCEG score recompute
- 2026-10-08 17:14 UTCMITRE cvelistV5first tracked
Related CVEs(same product + same CWE)
Same product
7 shownnpm:msgpack5
Frequently asked(5)
What is CVE-2026-107300?
CVE-2026-107300 is a high vulnerability published on October 8, 2026. msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the streaming decoder recursively invokes itself for each complete MessagePack value remaining in a chunk. A remote peer can send one chunk containing many small valid values, causing recursion proportional to the…
When was CVE-2026-107300 disclosed?
CVE-2026-107300 was first published on October 8, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-107300 actively exploited?
CVE-2026-107300 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (34th percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-107300?
CVE-2026-107300 has a CVSS base score of 7.5 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-107300?
A fix for CVE-2026-107300 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-107300 are linked in the Vendor Advisories panel on this page.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-107300
Is Your Infrastructure Affected by CVE-2026-107300?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.