CVE-2026-9155: OS Command Injection vulnerability in Rapid7 InsightConnect Sed Plugin on Linux allows authenticated attackers

This month

HIGH 8.8WATCHLISTDOWNGRADE

CVE-2026-9155 is a high-severity flaw (CVSS 8.8) affecting sed. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

OS Command Injection vulnerability in Rapid7 InsightConnect Sed Plugin on Linux allows authenticated attackers to execute arbitrary OS commands via the expression parameter due to insufficient input validation.

Why this priority

High severity
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	1.6% (top 24%)
CISA exploited list	No
Weakness	CWE-78
Published	2026-06-25
Last modified	2026-10-25

Publisher (CNA): Rapid7, Inc. · Vendor: gnu

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-25 01:16 UTCPublished CVE record published
2026-10-25 23:10 UTCUpdated Record last modified

gnu sed DOWNGRADE

Affected: 4.2.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.2.2

1. Check installed version

apt-cache policy sed || rpm -q sed || sed --version

2. No fixed release: DOWNGRADE to a release before 4.2.2 (Debian / Ubuntu)

apt-cache madison sed sudo apt install sed=<VERSION_BEFORE_4.2.2> sudo apt-mark hold sed

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list sed sudo dnf downgrade sed-<VERSION_BEFORE_4.2.2> sudo dnf versionlock add sed

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.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · mingw-qt5-qtwebkit · FIXED · 5.212.0-0.46.alpha4.fc46 · FEDORA-2026-46ae541c22 · source

sudo dnf upgrade --advisory=FEDORA-2026-46ae541c22

Fedora ELN · kdominate · FIXED · 26.08.2-2.eln159 · FEDORA-2026-b1d98239fd · source

sudo dnf upgrade --advisory=FEDORA-2026-b1d98239fd

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-2026-9155?

sed: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-9155 being exploited?

CVE-2026-9155 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-2026-9155 affect?

CVE-2026-9155 affects sed. Severity is high (CVSS 8.8). OS Command Injection vulnerability in Rapid7 InsightConnect Sed Plugin on Linux allows authenticated attackers to execute arbitrary OS commands via the expression parameter due to insufficient input validation.

How urgent is CVE-2026-9155?

Priority 55/100. High severity; On your watchlist

Related CVEs

CVE-2026-9154 HIGH 7.1 DOWNGRADE Arbitrary File Write vulnerability in Rapid7 InsightConnect Sed Plugin on Linux allows authenticated attackers
CVE-2026-9153 MEDIUM 6.5 DOWNGRADE Arbitrary File Read vulnerability in Rapid7 InsightConnect Sed Plugin on Linux allows authenticated attackers

References

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