CVE-2026-85440: MOOS core-moos through 10.4.0 contains a pre-authentication heap overflow vulnerability in MOOSCommPkt packet

Q: How do I fix CVE-2026-85440?

core-moos: upgrade to 10.4.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-85440 being exploited?

CVE-2026-85440 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-85440 affect?

CVE-2026-85440 affects core-moos. Severity is critical (CVSS 9.8). 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 sig

Q: How urgent is CVE-2026-85440?

Priority 55/100. Critical severity; Remotely exploitable, no login, no user action

This month

CRITICAL 9.8REMOTEUPGRADE

CVE-2026-85440 is a critical-severity flaw (CVSS 9.8) affecting core-moos. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.0% (top 37%)
CISA exploited list	No
Weakness	CWE-787
Published	2026-09-03
Last modified	2026-10-14

Publisher (CNA): VulnCheck · Vendor: themoos

Last updated 2026-10-14 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-03 23:17 UTCPublished CVE record published
2026-10-14 23:29 UTCUpdated Record last modified

themoos core-moos UPGRADE

Affected: < 10.4.0

Fixed in: 10.4.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy core-moos || rpm -q core-moos || core-moos --version

2. UPGRADE to 10.4.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade core-moos

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade core-moos

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-85440?

core-moos: upgrade to 10.4.0. Exact commands for each OS are on this page.

Is CVE-2026-85440 being exploited?

CVE-2026-85440 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-85440 affect?

CVE-2026-85440 affects core-moos. Severity is critical (CVSS 9.8). 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 sig

How urgent is CVE-2026-85440?

Priority 55/100. Critical severity; Remotely exploitable, no login, no user action

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References

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