CVE-2017-18635: An XSS vulnerability was discovered in noVNC before 0.6.2 in which the remote VNC server could inject arbitrar

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MEDIUM 6.1WATCHLISTUPGRADEMITIGATEMITIGATE

CVE-2017-18635 is a medium-severity flaw (CVSS 6.1) affecting novnc, debian linux, ubuntu linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An XSS vulnerability was discovered in noVNC before 0.6.2 in which the remote VNC server could inject arbitrary HTML into the noVNC web page via the messages propagated to the status field, such as the VNC server name.

Why this priority

EPSS top 8%: very likely to be exploited
Public exploit reference
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	4.8% (top 8%)
CISA exploited list	No
Weakness	CWE-79
Published	2019-09-25
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: canonical · debian · novnc · redhat

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2019-09-25 23:15 UTCPublished CVE record published
2026-06-17 01:13 UTCUpdated Record last modified

novnc novnc UPGRADE

Affected: < 0.6.2

Fixed in: 0.6.2

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 0.6.2 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade novnc

Note

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

debian debian linux MITIGATE

Affected: 8.0 · 9.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 8.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

canonical ubuntu linux MITIGATE

Affected: 16.04

Fixed in: no fixed release known

Safe to downgrade to: a release before 16.04

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

redhat openstack DOWNGRADE

Affected: 13

Fixed in: no fixed release known

Safe to downgrade to: a release before 13

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 13 (Debian / Ubuntu)

apt-cache madison openstack sudo apt install openstack=<VERSION_BEFORE_13> sudo apt-mark hold openstack

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list openstack sudo dnf downgrade openstack-<VERSION_BEFORE_13> sudo dnf versionlock add openstack

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-2017-18635?

novnc: upgrade to 0.6.2; debian linux: mitigate or apply the listed mitigation; ubuntu linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2017-18635 being exploited?

CVE-2017-18635 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-2017-18635 affect?

CVE-2017-18635 affects novnc, debian linux, ubuntu linux. Severity is medium (CVSS 6.1). An XSS vulnerability was discovered in noVNC before 0.6.2 in which the remote VNC server could inject arbitrary HTML into the noVNC web page via the messages propagated to the status field, such as the VNC server name.

How urgent is CVE-2017-18635?

Priority 54/100. EPSS top 8%: very likely to be exploited; Public exploit reference; On your watchlist

Software pages

Ubuntu vulnerabilities · Debian vulnerabilities · OpenStack vulnerabilities

References

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