CyberSecBulletin
CVE-2026-106500NVD status: Analyzed

backstage: Improper Link Resolution Before File Access

Published Updated By the CyberSecBulletin desk

CVE-2026-106500 is a high-severity improper link resolution before file access vulnerability in backstage, with a CVSS 3.1 base score of 8.5 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected backstage versions: < 1.49.6; >= 1.50.0-next.0, < 1.50.5; >= 1.51.0-next.0, < 1.54.6. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.34% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Backstage/plugin-scaffolder-backend to 3.3.1 or 3.4.1 or 4.0.3 or 4.1.0, whichever matches your release line, or a later version.
  2. Read the advisory on github.com for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
Backstagebackstage< 1.49.6; >= 1.50.0-next.0, < 1.50.5; >= 1.51.0-next.0, < 1.54.6Not stated
@backstageplugin-scaffolder-backend< 3.3.1; >= 3.4.0, < 3.4.1; >= 4.0.0, < 4.0.3; >= 4.0.4, < 4.1.0Not stated
Linux FoundationBackstage/plugin-scaffolder-backendbefore 3.3.1; 3.4.0 up to, but not including, 3.4.1; 4.0.0 up to, but not including, 4.0.3; 4.0.4 up to, but not including, 4.1.03.3.1, 3.4.1, 4.0.3, 4.1.0

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
HighSuccess depends on conditions outside the attacker's control.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
ChangedThe attack can reach beyond the vulnerable component into other systems.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H. Scored by CNA (github.com).

Official description

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 improper task state validation in scaffolder backend. An authenticated user with permission to create and access Scaffolder tasks may, under specific timing and deployment conditions, affect files accessible to the Backstage backend. If backend application files are writable, the confidentiality, integrity, and availability of the backend may be compromised. This issue is fixed in versions 3.3.1, 3.4.1, 4.0.3 and 4.1.0.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Improper Link Resolution Before File Access

The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

How developers prevent this class of flaw

  • Follow the principle of least privilege when assigning access rights to entities in a software system. Denying access to a file can prevent an attacker from replacing that file with a link to a sensitive file. Ensure good compartmentalization in the system to provide protected areas that can be trusted.

More Improper Link Resolution Before File Access vulnerabilities (CWE-59)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in backstage

All backstage vulnerabilities

Recent Improper Link Resolution Before File Access vulnerabilities

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