CyberSecBulletin
CVE-2026-1699NVD status: Analyzed

Eclipse Theia - Website: Inclusion of Functionality from Untrusted Control Sphere

Published Updated By the CyberSecBulletin desk

CVE-2026-1699 is a high-severity inclusion of functionality from untrusted control sphere vulnerability in Eclipse Theia - Website from Eclipse Foundation, with a CVSS 3.1 base score of 8.8 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. The record lists version 2fb0cc4bfc372cfaef79feb4eebb6563778b2560 as the first without the flaw, so updating Eclipse Theia - Website to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.55% 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 Eclipse Theia - Website to 2fb0cc4bfc372cfaef79feb4eebb6563778b2560 or a later version.
  2. Update Theia Website to 2026-01-22 or a later version.
  3. Read the advisory on gitlab.eclipse.org for workarounds and exact fixed builds.

Affected products and versions

VendorProductAffected versionsFixed in
Eclipse FoundationEclipse Theia - Websitebefore 2fb0cc4bfc372cfaef79feb4eebb6563778b25602fb0cc4bfc372cfaef79feb4eebb6563778b2560
EclipseTheia Websitebefore 2026-01-222026-01-22

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
LowNo special conditions are needed; the attack works reliably.
Privileges required
LowA basic user account is enough.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
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:L/PR:L/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.110.0CriticalCNA (eclipse.org)
CVSS 3.18.8HighNVD

Official description

In the Eclipse Theia Website repository, the GitHub Actions workflow .github/workflows/preview.yml used pull_request_target trigger while checking out and executing untrusted pull request code. This allowed any GitHub user to execute arbitrary code in the repository's CI environment with access to repository secrets and a GITHUB_TOKEN with extensive write permissions (contents:write, packages:write, pages:write, actions:write). An attacker could exfiltrate secrets, publish malicious packages to the eclipse-theia organization, modify the official Theia website, and push malicious code to the repository.

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

The underlying weakness: Inclusion of Functionality from Untrusted Control Sphere

The product imports, requires, or includes executable functionality (such as a library) from a source that is outside of the intended control sphere.

How developers prevent this class of flaw

  • Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
  • When the set of acceptable objects, such as filenames or URLs, is limited or known, create a mapping from a set of fixed input values (such as numeric IDs) to the actual filenames or URLs, and reject all other inputs. For example, ID 1 could map to inbox.txt and ID 2 could map to profile.txt. Features such as the ESAPI AccessReferenceMap provide this capability.
  • For any security checks that are performed on the client side, ensure that these checks are duplicated on the server side, in order to avoid CWE-602. Attackers can bypass the client-side checks by modifying values after the checks have been performed, or by changing the client to remove the client-side checks entirely. Then, these modified values would be submitted to the server.

More Inclusion of Functionality from Untrusted Control Sphere vulnerabilities (CWE-829)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: poc, automatable: yes, technical impact: total).
  3. Record last changed materially (score, affected products, status or references).

References

Recent Inclusion of Functionality from Untrusted Control Sphere vulnerabilities

Spotted an error? Tell us.