Buffer overflow in Themoos Core-Moos
CVE-2026-85440
MOOS core-moos through 10.4.0 contains a pre-authentication heap overflow vulnerability in MOOSCommPkt packet handling that allows remote attackers to write arbitrary data by declaring a negative packet length. Attackers can exploit the signed integer check in InflateTo() and negative size conversion in recv() to overflow a four-byte heap buffer during the HandShake phase before authentication.
Vulnerability class: Buffer Overflow
Published · last modified .
CVSS v3 metric
CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.
EPSS exploit prediction
EPSS: 0.010 (63.0th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 63rd percentile — 63.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.010 · change: +0.005
Affected products
Weakness classification (CWE)
References
- github.com/themoos/core-moos (Product, product)
- github.com/themoos/core-moos/blob/ec9c77c68fcbdef8f5e4c60fe243acd223433f0c/Core… (technical-description, Patch, Issue Tracking)
- github.com/themoos/core-moos/commit/96c49c5cdda6e07ee734a5324e8d25ba5a7f2d7a (Patch, patch, Issue Tracking)
- github.com/themoos/core-moos/pull/82 (issue-tracking, Patch, patch, Issue Tracking)
- www.vulncheck.com/advisories/moos-core-moos-through-10.4.0-moosdb-pre-authentic… (Third Party Advisory, third-party-advisory)
Frequently asked questions
- What is CVE-2026-85440?
- CVE-2026-85440 is a critical-severity vulnerability in Themoos Core-Moos, classified under Out-of-bounds Write. CVSS score: 9.8/10. Published 2026-09-03.
- How severe is CVE-2026-85440?
- Critical severity. CVSS v3 base score is 9.8 out of 10.