CVE-2026-5366: Prefect version 3.6.23 is vulnerable to remote code execution due to improper handling of user-controlled inpu

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CRITICAL 9.9DOWNGRADE

CVE-2026-5366 is a critical-severity flaw (CVSS 9.9) affecting prefect. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Prefect version 3.6.23 is vulnerable to remote code execution due to improper handling of user-controlled input in the `GitRepository` storage class. The `commit_sha` parameter, which is passed to git commands, lacks validation and does not include a `--` separator to distinguish user input from git flags. This allows attackers to inject arbitrary git flags, such as `--upload-pack`, enabling execution of external programs. Additionally, the `dire

Why this priority

Critical severity
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	9.9 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	1.0% (top 36%)
CISA exploited list	No
Weakness	CWE-94
Published	2026-06-20
Last modified	2026-10-25

Publisher (CNA): huntr.dev · Vendor: prefect

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

Am I affected?

Timeline

2026-06-20 17:16 UTCPublished CVE record published
2026-10-25 23:10 UTCUpdated Record last modified

prefect prefect DOWNGRADE

Affected: 3.6.23

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.6.23

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 3.6.23 (Debian / Ubuntu)

apt-cache madison prefect sudo apt install prefect=<VERSION_BEFORE_3.6.23> sudo apt-mark hold prefect

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

dnf --showduplicates list prefect sudo dnf downgrade prefect-<VERSION_BEFORE_3.6.23> sudo dnf versionlock add prefect

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

Public exploits and detection

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

GitHub PoC: renat0z3r0/prefect-cve-2026-5366 (0 stars)

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-2026-5366?

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

Is CVE-2026-5366 being exploited?

CVE-2026-5366 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-2026-5366 affect?

CVE-2026-5366 affects prefect. Severity is critical (CVSS 9.9). Prefect version 3.6.23 is vulnerable to remote code execution due to improper handling of user-controlled input in the `GitRepository` storage class. The `commit_sha` parameter, which is passed to git commands, lacks validation and does not

How urgent is CVE-2026-5366?

Priority 56/100. Critical severity; Public exploit reference

Software pages

Git vulnerabilities

References

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