CVE-2026-61891: In Eclipse Theia versions up to and including 1.73.1, the `@theia/filesystem` backend exposes HTTP file-downlo

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HIGH 7.5REMOTEUPGRADE

CVE-2026-61891 is a high-severity flaw (CVSS 7.5) affecting theia. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In Eclipse Theia versions up to and including 1.73.1, the `@theia/filesystem` backend exposes HTTP file-download endpoints (`GET /file`, `GET /files/`, `PUT /files/`) that convert a client-supplied URI directly to a filesystem path and stream the file, without confining it to the workspace or any allow-listed root. In browser (non-Electron) deployments the connection token is enforced only on WebSocket upgrades; the HTTP middleware in `@theia/cor

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 56%)
CISA exploited list	No
Weakness	CWE-22, CWE-36, CWE-200, CWE-306
Published	2026-08-05
Last modified	2026-10-23

Publisher (CNA): Eclipse Foundation · Vendor: eclipse

Am I affected?

Timeline

2026-08-05 12:18 UTCPublished CVE record published
2026-10-23 21:10 UTCUpdated Record last modified

eclipse theia UPGRADE

Affected: < 1.74.0

Fixed in: 1.74.0

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 1.74.0 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade theia

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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.

Related CVEs

CVE-2026-12609 HIGH 7.5 UPGRADE In Eclipse Theia versions 1.66.0 and up until including 1.73.1, the `@theia/plugin-ext` backend exposes the `/
CVE-2026-60009 HIGH 8.8 UPGRADE In Eclipse Theia versions up to and including 1.73.1, the `@theia/filesystem` backend binds `POST /file-upload
CVE-2026-14574 MEDIUM 6.5 UPGRADE In Eclipse Theia versions 0.7.0 and up until including 1.73.1, the `PreferenceUtils.merge` function in `@theia

References

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