CVE-2026-14574: In Eclipse Theia versions 0.7.0 and up until including 1.73.1, the `PreferenceUtils.merge` function in `@theia

Routine

MEDIUM 6.5UPGRADE

CVE-2026-14574 is a medium-severity flaw (CVSS 6.5) affecting theia. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In Eclipse Theia versions 0.7.0 and up until including 1.73.1, the `PreferenceUtils.merge` function in `@theia/core` recursively merges preference values without rejecting prototype-related keys (`__proto__`, `constructor`, `prototype`). Because this function is invoked by `PreferenceServiceImpl.doResolve` for every preference resolution across scopes (default, user, workspace, folder), a crafted preference value in a workspace settings file (`.t

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.4% (top 67%)
CISA exploited list	No
Weakness	CWE-1321
Published	2026-08-05
Last modified	2026-10-23

Publisher (CNA): Eclipse Foundation · Vendor: eclipse

Am I affected?

Timeline

2026-08-05 11:16 UTCPublished CVE record published
2026-10-23 21:10 UTCUpdated Record last modified

eclipse theia UPGRADE

Affected: >= 0.7.0 and < 1.74.0

Fixed in: 1.74.0

Safe to downgrade to: a release before 0.7.0

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.

3. If no update is available yet, DOWNGRADE to a release before 0.7.0 (Debian / Ubuntu)

apt-cache madison theia sudo apt install theia=<VERSION_BEFORE_0.7.0> sudo apt-mark hold theia

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

dnf --showduplicates list theia sudo dnf downgrade theia-<VERSION_BEFORE_0.7.0> sudo dnf versionlock add theia

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-2026-14574?

theia: upgrade to 1.74.0. Exact commands for each OS are on this page.

Is CVE-2026-14574 being exploited?

CVE-2026-14574 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-2026-14574 affect?

CVE-2026-14574 affects theia. Severity is medium (CVSS 6.5). In Eclipse Theia versions 0.7.0 and up until including 1.73.1, the `PreferenceUtils.merge` function in `@theia/core` recursively merges preference values without rejecting prototype-related keys (`__proto__`, `constructor`, `prototype`). Be

How urgent is CVE-2026-14574?

Priority 36/100. Public exploit reference

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References

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