CVE-2020-29074: scan.c in x11vnc 0.9.16 uses IPC_CREAT|0777 in shmget calls, which allows access by actors other than the curr

This month

HIGH 8.8WATCHLISTDOWNGRADEMITIGATEMITIGATE

CVE-2020-29074 is a high-severity flaw (CVSS 8.8) affecting x11vnc, fedora, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

scan.c in x11vnc 0.9.16 uses IPC_CREAT|0777 in shmget calls, which allows access by actors other than the current user.

Why this priority

High severity
On your watchlist

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	8.8 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	1.8% (top 22%)
CISA exploited list	No
Weakness	CWE-732
Published	2020-11-25
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: debian · fedoraproject · x11vnc project

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

Am I affected?

Timeline

2020-11-25 23:15 UTCPublished CVE record published
2026-06-17 03:11 UTCUpdated Record last modified

x11vnc project x11vnc DOWNGRADE

Affected: 0.9.16

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.9.16

1. Check installed version

apt-cache policy x11vnc || rpm -q x11vnc || x11vnc --version

2. No fixed release: DOWNGRADE to a release before 0.9.16 (Debian / Ubuntu)

apt-cache madison x11vnc sudo apt install x11vnc=<VERSION_BEFORE_0.9.16> sudo apt-mark hold x11vnc

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

dnf --showduplicates list x11vnc sudo dnf downgrade x11vnc-<VERSION_BEFORE_0.9.16> sudo dnf versionlock add x11vnc

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.

fedoraproject fedora MITIGATE

Affected: 32 · 33 · 34

Fixed in: no fixed release known

Safe to downgrade to: a release before 32

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.

debian debian linux MITIGATE

Affected: 9.0 · 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 9.0

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.

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-2020-29074?

x11vnc: downgrade or apply the listed mitigation; fedora: mitigate or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-29074 being exploited?

CVE-2020-29074 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-2020-29074 affect?

CVE-2020-29074 affects x11vnc, fedora, debian linux. Severity is high (CVSS 8.8). scan.c in x11vnc 0.9.16 uses IPC_CREAT|0777 in shmget calls, which allows access by actors other than the current user.

How urgent is CVE-2020-29074?

Priority 55/100. High severity; On your watchlist

Software pages

Debian vulnerabilities

References

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