CVE-2026-9186: IBM Langflow OSS 1.0.0 through 1.11.2 allows remote authenticated attackers to bypass localhost-only MCP confi

Routine

MEDIUM 6.5UPGRADE

CVE-2026-9186 is a medium-severity flaw (CVSS 6.5) affecting langflow. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

IBM Langflow OSS 1.0.0 through 1.11.2 allows remote authenticated attackers to bypass localhost-only MCP configuration installation by spoofing X-Forwarded-For: 127.0.0.1 header, enabling arbitrary writes to IDE config files (~/.cursor/mcp.json, etc.).

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.4% (top 68%)
CISA exploited list	No
Weakness	CWE-284
Published	2026-09-04
Last modified	2026-09-08

Publisher (CNA): IBM Corporation · Vendor: langflow

Last updated 2026-09-08 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-04 15:17 UTCPublished CVE record published
2026-09-08 21:45 UTCUpdated Record last modified

langflow langflow UPGRADE

Affected: >= 1.0.0 and < 1.11.3

Fixed in: 1.11.3

Safe to downgrade to: a release before 1.0.0

1. Check installed version

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

2. UPGRADE to 1.11.3 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade langflow

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade langflow

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 1.0.0 (Debian / Ubuntu)

apt-cache madison langflow sudo apt install langflow=<VERSION_BEFORE_1.0.0> sudo apt-mark hold langflow

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

dnf --showduplicates list langflow sudo dnf downgrade langflow-<VERSION_BEFORE_1.0.0> sudo dnf versionlock add langflow

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-2026-9186?

langflow: upgrade to 1.11.3. Exact commands for each OS are on this page.

Is CVE-2026-9186 being exploited?

CVE-2026-9186 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-2026-9186 affect?

CVE-2026-9186 affects langflow. Severity is medium (CVSS 6.5). IBM Langflow OSS 1.0.0 through 1.11.2 allows remote authenticated attackers to bypass localhost-only MCP configuration installation by spoofing X-Forwarded-For: 127.0.0.1 header, enabling arbitrary writes to IDE config files (~/.cursor/mcp.

How urgent is CVE-2026-9186?

Priority 31/100. No elevated risk signals yet.

Related CVEs

CVE-2026-34046 HIGH 8.8 UPGRADE UPGRADE Langflow is a tool for building and deploying AI-powered agents and workflows
CVE-2026-6542 MEDIUM 6.5 UPGRADE IBM Langflow OSS 1.0.0 through 1.8.4 could allow any user to supply a flow_id to read transaction logs and ver
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References

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