CVE-2026-30803: Integer Underflow (Wrap or Wraparound) vulnerability in RTI Connext Micro (Core Libraries) allows Overread Buf

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CRITICAL 9.1REMOTEUPGRADE

CVE-2026-30803 is a critical-severity flaw (CVSS 9.1) affecting connext micro. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Integer Underflow (Wrap or Wraparound) vulnerability in RTI Connext Micro (Core Libraries) allows Overread Buffers. This issue affects Connext Micro: from 4.0.0 before 4.3.0.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 78%)
CISA exploited list	No
Weakness	CWE-191
Published	2026-06-17
Last modified	2026-10-26

Publisher (CNA): RTI · Vendor: rti

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-17 18:17 UTCPublished CVE record published
2026-10-26 11:10 UTCUpdated Record last modified

rti connext micro UPGRADE

Affected: >= 4.0.0 and < 4.3.0

Fixed in: 4.3.0

Safe to downgrade to: a release before 4.0.0

1. Check installed version

apt-cache policy connext-micro || rpm -q connext-micro || connext-micro --version

2. UPGRADE to 4.3.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade connext-micro

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade connext-micro

Note

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

3. If no update is available yet, DOWNGRADE to a release before 4.0.0 (Debian / Ubuntu)

apt-cache madison connext-micro sudo apt install connext-micro=<VERSION_BEFORE_4.0.0> sudo apt-mark hold connext-micro

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list connext-micro sudo dnf downgrade connext-micro-<VERSION_BEFORE_4.0.0> sudo dnf versionlock add connext-micro

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

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-2026-30803?

connext micro: upgrade to 4.3.0. Exact commands for each OS are on this page.

Is CVE-2026-30803 being exploited?

CVE-2026-30803 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-2026-30803 affect?

CVE-2026-30803 affects connext micro. Severity is critical (CVSS 9.1). Integer Underflow (Wrap or Wraparound) vulnerability in RTI Connext Micro (Core Libraries) allows Overread Buffers. This issue affects Connext Micro: from 4.0.0 before 4.3.0.

How urgent is CVE-2026-30803?

Priority 42/100. Critical severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2026-30802 HIGH 8.2 UPGRADE Out-of-bounds Read vulnerability in RTI Connext Micro (Core Libraries) allows Overread Buffers

References

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