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CVE-2026-12940: IBM Langflow OSS 1.0.0 through 1.10.1  are vulnerable to unauthenticated remote code execution via environment

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CRITICAL 9.8REMOTEUPGRADE

CVE-2026-12940 is a critical-severity flaw (CVSS 9.8) 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 1.10.1  are vulnerable to unauthenticated remote code execution via environment variable injection in the MCP (Model Context Protocol) stdio launcher. The vulnerability exists in src/lfx/src/lfx/base/mcp/util.py where the DANGEROUS_ENV_VARS blocklist fails to include SHELLOPTS , BASHOPTS , and PS4 environment variables.

Why this priority

  • Critical severity
  • CISA SSVC: automatable with total technical impact
  • Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score9.8 (Critical)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededNone
User interactionNone
EPSS exploit chance0.9% (top 39%)
CISA exploited listNo
WeaknessCWE-78
Published2026-07-30
Last modified2026-10-23
Publisher (CNA): IBM Corporation · Vendor: langflow

Last updated 2026-10-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

langflow langflow UPGRADE
Affected: >= 1.0.0 and < 1.10.2
Fixed in: 1.10.2
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 1.10.2 (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.

Exact fixes by distribution

Fedora 46 · pspp · FIXED · 2.1.3-2.fc46 · FEDORA-2026-0d6444911b · source
sudo dnf upgrade --advisory=FEDORA-2026-0d6444911b
Fedora ELN · barman · FIXED · 3.20.1-3.eln159 · FEDORA-2026-45ecf042c2 · source
sudo dnf upgrade --advisory=FEDORA-2026-45ecf042c2

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

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-2026-12940?

langflow: upgrade to 1.10.2. Exact commands for each OS are on this page.

Is CVE-2026-12940 being exploited?

CVE-2026-12940 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-2026-12940 affect?

CVE-2026-12940 affects langflow. Severity is critical (CVSS 9.8). IBM Langflow OSS 1.0.0 through 1.10.1  are vulnerable to unauthenticated remote code execution via environment variable injection in the MCP (Model Context Protocol) stdio launcher. The vulnerability exists in src/lfx/src/lfx/base/mcp/util.

How urgent is CVE-2026-12940?

Priority 57/100. Critical severity; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Related CVEs

References

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