CVE-2026-39847: Emmett is a full-stack Python web framework designed with simplicity

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CRITICAL 9.1REMOTEUPGRADE

CVE-2026-39847 is a critical-severity flaw (CVSS 9.1) affecting emmett. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Emmett is a full-stack Python web framework designed with simplicity. From 2.5.0 to before 2.8.1, the RSGI static handler for Emmett's internal assets (/__emmett__ paths) is vulnerable to path traversal attacks. An attacker can use ../ sequences (eg /__emmett__/../rsgi/handlers.py) to read arbitrary files outside the assets directory. This vulnerability is fixed in 2.8.1.

Why this priority

Critical severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 58%)
CISA exploited list	No
Weakness	CWE-22
Published	2026-04-07
Last modified	2026-07-24

Publisher (CNA): GitHub, Inc. · Vendor: emmett

Last updated 2026-07-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-07 22:16 UTCPublished CVE record published
2026-07-24 21:10 UTCUpdated Record last modified

emmett emmett UPGRADE

Affected: >= 2.5.0 and < 2.8.1

Fixed in: 2.8.1

Safe to downgrade to: a release before 2.5.0

1. Check installed version

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

2. UPGRADE to 2.8.1 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade emmett

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 2.5.0 (Debian / Ubuntu)

apt-cache madison emmett sudo apt install emmett=<VERSION_BEFORE_2.5.0> sudo apt-mark hold emmett

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

dnf --showduplicates list emmett sudo dnf downgrade emmett-<VERSION_BEFORE_2.5.0> sudo dnf versionlock add emmett

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-2026-39847?

emmett: upgrade to 2.8.1. Exact commands for each OS are on this page.

Is CVE-2026-39847 being exploited?

CVE-2026-39847 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-2026-39847 affect?

CVE-2026-39847 affects emmett. Severity is critical (CVSS 9.1). Emmett is a full-stack Python web framework designed with simplicity. From 2.5.0 to before 2.8.1, the RSGI static handler for Emmett's internal assets (/__emmett__ paths) is vulnerable to path traversal attacks. An attacker can use ../ sequ

How urgent is CVE-2026-39847?

Priority 47/100. Critical severity; Remotely exploitable, no login, no user action

Software pages

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References

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