CVE-2026-66881: Relative Path Traversal vulnerability in livebook-dev livebook allows an attacker-authored notebook to write a

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HIGH 8.1UPGRADE

CVE-2026-66881 is a high-severity flaw (CVSS 8.1) affecting livebook. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Relative Path Traversal vulnerability in livebook-dev livebook allows an attacker-authored notebook to write a file with attacker-controlled content to an arbitrary path. A .livemd notebook can declare file_entries metadata, each entry carrying a name. Every path that creates a file entry through the user interface validates that name with Livebook.Notebook.validate_file_entry_name/2, which requires a flat filename of alphanumerics, dashes, unde

Why this priority

High severity
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.6% (top 51%)
CISA exploited list	No
Weakness	CWE-23
Published	2026-08-05
Last modified	2026-10-23

Publisher (CNA): EEF · Vendor: livebook

Am I affected?

Timeline

2026-08-05 20:17 UTCPublished CVE record published
2026-10-23 21:10 UTCUpdated Record last modified

livebook livebook UPGRADE

Affected: >= 0.11.0 and < 0.18.7 · >= 0.19.0 and < 0.19.9

Fixed in: 0.18.7, 0.19.9

Safe to downgrade to: a release before 0.11.0

1. Check installed version

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

2. UPGRADE to 0.18.7 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade livebook

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 0.11.0 (Debian / Ubuntu)

apt-cache madison livebook sudo apt install livebook=<VERSION_BEFORE_0.11.0> sudo apt-mark hold livebook

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

dnf --showduplicates list livebook sudo dnf downgrade livebook-<VERSION_BEFORE_0.11.0> sudo dnf versionlock add livebook

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 · kwin-zones · FIXED · 1.0.13-1.fc46 · FEDORA-2026-95888f332b · source

sudo dnf upgrade --advisory=FEDORA-2026-95888f332b

Fedora ELN · nginx-mod-brotli · FIXED · 1.0.0~rc-16.eln159 · FEDORA-2026-501a6a8273 · source

sudo dnf upgrade --advisory=FEDORA-2026-501a6a8273

Public exploits and detection

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

Write-up: github.com/livebook-dev/livebook/security/advisories/GHSA-r4h8-2xpq-v48g

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.

Related CVEs

CVE-2026-66297 HIGH 8.0 UPGRADE Improper Neutralization of Special Elements used in an OS Command (OS Command Injection) vulnerability in live
CVE-2026-68746 HIGH 8.8 UPGRADE Not Failing Securely ('Failing Open') vulnerability in livebook-dev livebook allows an unauthenticated network
CVE-2026-66298 HIGH 8.8 UPGRADE Origin Validation Error vulnerability in livebook-dev livebook allows untrusted notebook output JavaScript to
CVE-2026-66885 MEDIUM 6.5 UPGRADE Cross-Site Request Forgery (CSRF) vulnerability in livebook-dev livebook allows an attacker to authenticate a

References

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