CVE-2026-35208: lichess.org is the forever free, adless and open source chess server

Q: How do I fix CVE-2026-35208?

lila: upgrade to 2026-03-31. Exact commands for each OS are on this page.

Q: Is CVE-2026-35208 being exploited?

CVE-2026-35208 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-35208 affect?

CVE-2026-35208 affects lila. Severity is medium (CVSS 5.4). lichess.org is the forever free, adless and open source chess server. Any approved streamer can inject arbitrary HTML into /streamer and the homepage “Live streams” widget by placing markup in their Twitch/YouTube stream title. CSP is prese

Q: How urgent is CVE-2026-35208?

Priority 30/100. Public exploit reference

Routine

MEDIUM 5.4UPGRADE

CVE-2026-35208 is a medium-severity flaw (CVSS 5.4) affecting lila. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

lichess.org is the forever free, adless and open source chess server. Any approved streamer can inject arbitrary HTML into /streamer and the homepage “Live streams” widget by placing markup in their Twitch/YouTube stream title. CSP is present and blocks inline script execution, but the issue is still a server-side HTML injection sink. To trigger this, a Lichess account only needs to satisfy the normal streamer requirements and get approved. Per S

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	5.4 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	Required
EPSS exploit chance	0.3% (top 78%)
CISA exploited list	No
Weakness	CWE-79, CWE-116
Published	2026-04-06
Last modified	2026-07-24

Publisher (CNA): GitHub, Inc. · Vendor: lichess

Last updated 2026-07-24 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-04-06 21:16 UTCPublished CVE record published
2026-07-24 21:10 UTCUpdated Record last modified

lichess lila UPGRADE

Affected: < 2026-03-31

Fixed in: 2026-03-31

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 2026-03-31 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade lila

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.

Quick answers

How do I fix CVE-2026-35208?

lila: upgrade to 2026-03-31. Exact commands for each OS are on this page.

Is CVE-2026-35208 being exploited?

CVE-2026-35208 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-2026-35208 affect?

CVE-2026-35208 affects lila. Severity is medium (CVSS 5.4). lichess.org is the forever free, adless and open source chess server. Any approved streamer can inject arbitrary HTML into /streamer and the homepage “Live streams” widget by placing markup in their Twitch/YouTube stream title. CSP is prese

How urgent is CVE-2026-35208?

Priority 30/100. Public exploit reference

References

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