CVE-2026-4983: Open VSX Registry does not sanitize SVG files uploaded as extension icons prior to storage, and serves them wi

Routine

MEDIUM 4.1UPGRADE

CVE-2026-4983 is a medium-severity flaw (CVSS 4.1) affecting open vsx. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Open VSX Registry does not sanitize SVG files uploaded as extension icons prior to storage, and serves them with Content-Type: image/svg+xml without security headers such as Content-Security-Policy or Content-Disposition: attachment. This allows an attacker to publish an extension with a malicious SVG icon and achieve stored cross-site scripting (XSS) when a user navigates directly to the icon URL. On deployments using local storage, script e

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	4.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.3% (top 76%)
CISA exploited list	No
Weakness	CWE-79
Published	2026-06-23
Last modified	2026-10-25

Publisher (CNA): Eclipse Foundation · Vendor: eclipse

Last updated 2026-10-25 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-23 12:16 UTCPublished CVE record published
2026-10-25 23:10 UTCUpdated Record last modified

eclipse open vsx UPGRADE

Affected: >= 0.1.0 and < 0.34.1

Fixed in: 0.34.1

Safe to downgrade to: a release before 0.1.0

1. Check installed version

apt-cache policy open-vsx || rpm -q open-vsx || open-vsx --version

2. UPGRADE to 0.34.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade open-vsx

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade open-vsx

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 0.1.0 (Debian / Ubuntu)

apt-cache madison open-vsx sudo apt install open-vsx=<VERSION_BEFORE_0.1.0> sudo apt-mark hold open-vsx

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

dnf --showduplicates list open-vsx sudo dnf downgrade open-vsx-<VERSION_BEFORE_0.1.0> sudo dnf versionlock add open-vsx

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-2026-4983?

open vsx: upgrade to 0.34.1. Exact commands for each OS are on this page.

Is CVE-2026-4983 being exploited?

CVE-2026-4983 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-2026-4983 affect?

CVE-2026-4983 affects open vsx. Severity is medium (CVSS 4.1). Open VSX Registry does not sanitize SVG files uploaded as extension icons prior to storage, and serves them with Content-Type: image/svg+xml without security headers such as Content-Security-Policy or Content-Disposition: attachment. This a

How urgent is CVE-2026-4983?

Priority 25/100. Public exploit reference

Related CVEs

CVE-2026-13323 MEDIUM 4.1 UPGRADE In Open VSX Registry before 1.0.2, the /vscode/unpkg/ endpoint serves user-supplied HTML files with Content-Ty

References

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