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CVE-2026-106503: Backstage is an open framework for building developer portals

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HIGH 8.1WATCHLISTUPGRADEUPGRADE

CVE-2026-106503 is a high-severity flaw (CVSS 8.1) affecting backstage\/plugin-scaffolder-backend, backstage. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Backstage is an open framework for building developer portals. Prior to 3.3.1, 3.4.1, 4.0.3 and 4.1.0, the @backstage/plugin-scaffolder-backend package is affected by scaffolder action input authorization bypass. An authenticated user with access to affected Scaffolder templates could bypass configured action restrictions. Depending on integration credentials, this could grant unauthorized access to repositories and related source-control resourc

Why this priority

  • High severity
  • On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score8.1 (High)
Attack vectorNetwork (remote)
Attack complexityLow
Privileges neededLow
User interactionNone
EPSS exploit chance0.4% (top 67%)
CISA exploited listNo
WeaknessCWE-178, CWE-284
Published2026-10-06
Last modified2026-10-13
Publisher (CNA): GitHub, Inc. · Vendor: linuxfoundation

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Last updated 2026-10-13 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

linuxfoundation backstage\/plugin-scaffolder-backend UPGRADE
Affected: < 3.3.1 · >= 3.4.0 and < 3.4.1 · >= 4.0.0 and < 4.0.3 · >= 4.0.4 and < 4.1.0
Fixed in: 3.3.1, 3.4.1, 4.0.3, 4.1.0
Safe to downgrade to: a release before 3.4.0
1. Check installed version
apt-cache policy backstageplugin-scaffolder-backend || rpm -q backstageplugin-scaffolder-backend || backstageplugin-scaffolder-backend --version
2. UPGRADE to 3.3.1 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade backstageplugin-scaffolder-backend
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade backstageplugin-scaffolder-backend
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 3.4.0 (Debian / Ubuntu)
apt-cache madison backstageplugin-scaffolder-backend sudo apt install backstageplugin-scaffolder-backend=<VERSION_BEFORE_3.4.0> sudo apt-mark hold backstageplugin-scaffolder-backend
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list backstageplugin-scaffolder-backend sudo dnf downgrade backstageplugin-scaffolder-backend-<VERSION_BEFORE_3.4.0> sudo dnf versionlock add backstageplugin-scaffolder-backend
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.
linuxfoundation backstage UPGRADE
Affected: < 1.49.6 · >= 1.50.0 and < 1.50.5 · >= 1.51.0 and < 1.54.6
Fixed in: 1.49.6, 1.50.5, 1.54.6
Safe to downgrade to: a release before 1.50.0
1. Check installed version
apt-cache policy backstage || rpm -q backstage || backstage --version
2. UPGRADE to 1.49.6 (Debian / Ubuntu)
sudo apt update && sudo apt install --only-upgrade backstage
2. UPGRADE (RHEL / Amazon Linux / Fedora)
sudo dnf upgrade backstage
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 1.50.0 (Debian / Ubuntu)
apt-cache madison backstage sudo apt install backstage=<VERSION_BEFORE_1.50.0> sudo apt-mark hold backstage
3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)
dnf --showduplicates list backstage sudo dnf downgrade backstage-<VERSION_BEFORE_1.50.0> sudo dnf versionlock add backstage
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-2026-106503?

backstage\/plugin-scaffolder-backend: upgrade to 3.3.1, 3.4.1, 4.0.3, 4.1.0; backstage: upgrade to 1.49.6, 1.50.5, 1.54.6. Exact commands for each OS are on this page.

Is CVE-2026-106503 being exploited?

CVE-2026-106503 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-2026-106503 affect?

CVE-2026-106503 affects backstage\/plugin-scaffolder-backend, backstage. Severity is high (CVSS 8.1). Backstage is an open framework for building developer portals. Prior to 3.3.1, 3.4.1, 4.0.3 and 4.1.0, the @backstage/plugin-scaffolder-backend package is affected by scaffolder action input authorization bypass. An authenticated user with

How urgent is CVE-2026-106503?

Priority 42/100. High severity; On your watchlist

Related CVEs

References

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