CVE-2021-29451: Portofino is an open source web development framework

This month

CRITICAL 9.1REMOTEUPGRADE

CVE-2021-29451 is a critical-severity flaw (CVSS 9.1) affecting portofino. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Portofino is an open source web development framework. Portofino before version 5.2.1 did not properly verify the signature of JSON Web Tokens. This allows forging a valid JWT. The issue will be patched in the upcoming 5.2.1 release.

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	0.9% (top 39%)
CISA exploited list	No
Weakness	CWE-347
Published	2021-04-16
Last modified	2026-06-17

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

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-04-16 22:15 UTCPublished CVE record published
2026-06-17 03:47 UTCUpdated Record last modified

manydesigns portofino UPGRADE

Affected: >= 5.0.0 and < 5.2.1

Fixed in: 5.2.1

Safe to downgrade to: a release before 5.0.0

1. Check installed version

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

2. UPGRADE to 5.2.1 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade portofino

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 5.0.0 (Debian / Ubuntu)

apt-cache madison portofino sudo apt install portofino=<VERSION_BEFORE_5.0.0> sudo apt-mark hold portofino

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

dnf --showduplicates list portofino sudo dnf downgrade portofino-<VERSION_BEFORE_5.0.0> sudo dnf versionlock add portofino

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-2021-29451?

portofino: upgrade to 5.2.1. Exact commands for each OS are on this page.

Is CVE-2021-29451 being exploited?

CVE-2021-29451 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-2021-29451 affect?

CVE-2021-29451 affects portofino. Severity is critical (CVSS 9.1). Portofino is an open source web development framework. Portofino before version 5.2.1 did not properly verify the signature of JSON Web Tokens. This allows forging a valid JWT. The issue will be patched in the upcoming 5.2.1 release.

How urgent is CVE-2021-29451?

Priority 52/100. Critical severity; Remotely exploitable, no login, no user action

Related CVEs

CVE-2022-3952 LOW 2.6 DOWNGRADE A vulnerability has been found in ManyDesigns Portofino 5.3.2 and classified as problematic

References

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