CVE-2020-13775: ZNC 1.8.0 up to 1.8.1-rc1 allows authenticated users to trigger an application crash (with a NULL pointer dere

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MEDIUM 6.5DOWNGRADEMITIGATE

CVE-2020-13775 is a medium-severity flaw (CVSS 6.5) affecting znc, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

ZNC 1.8.0 up to 1.8.1-rc1 allows authenticated users to trigger an application crash (with a NULL pointer dereference) if echo-message is not enabled and there is no network.

Why this priority

No elevated risk signals yet

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

Risk facts

CVSS score	6.5 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	1.8% (top 21%)
CISA exploited list	No
Weakness	CWE-476
Published	2020-06-02
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: fedoraproject · znc

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

Am I affected?

Timeline

2020-06-02 23:15 UTCPublished CVE record published
2026-06-17 02:53 UTCUpdated Record last modified

znc znc DOWNGRADE

Affected: 1.8.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.8.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.8.0 (Debian / Ubuntu)

apt-cache madison znc sudo apt install znc=<VERSION_BEFORE_1.8.0> sudo apt-mark hold znc

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

dnf --showduplicates list znc sudo dnf downgrade znc-<VERSION_BEFORE_1.8.0> sudo dnf versionlock add znc

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: 31 · 32

Fixed in: no fixed release known

Safe to downgrade to: a release before 31

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-2020-13775?

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

Is CVE-2020-13775 being exploited?

CVE-2020-13775 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-2020-13775 affect?

CVE-2020-13775 affects znc, fedora. Severity is medium (CVSS 6.5). ZNC 1.8.0 up to 1.8.1-rc1 allows authenticated users to trigger an application crash (with a NULL pointer dereference) if echo-message is not enabled and there is no network.

How urgent is CVE-2020-13775?

Priority 43/100. No elevated risk signals yet.

Related CVEs

CVE-2019-9917 MEDIUM 6.5 UPGRADE MITIGATE ZNC before 1.7.3-rc1 allows an existing remote user to cause a Denial of Service (crash) via invalid encoding.
CVE-2019-12816 HIGH 8.8 UPGRADE Modules.cpp in ZNC before 1.7.4-rc1 allows remote authenticated non-admin users to escalate privileges and exe
CVE-2018-14056 MEDIUM 5.3 UPGRADE MITIGATE ZNC before 1.7.1-rc1 is prone to a path traversal flaw via ../ in a web skin name to access files outside of t
CVE-2018-14055 MEDIUM 6.5 UPGRADE MITIGATE ZNC before 1.7.1-rc1 does not properly validate untrusted lines coming from the network, allowing a non-admin
CVE-2014-9403 MEDIUM 4.0 UPGRADE The CWebAdminMod::ChanPage function in modules/webadmin.cpp in ZNC before 1.4 allows remote authenticated user

References

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