CVE-2020-15956: ActiveMediaServer.exe in ACTi NVR3 Standard Server 3.0.12.42 allows remote unauthenticated attackers to trigge

This week

HIGH 7.5REMOTEDOWNGRADE

CVE-2020-15956 is a high-severity flaw (CVSS 7.5) affecting nvr. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

ActiveMediaServer.exe in ACTi NVR3 Standard Server 3.0.12.42 allows remote unauthenticated attackers to trigger a buffer overflow and application termination via a malformed payload.

Why this priority

High severity
EPSS top 3%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	16.2% (top 3%)
CISA exploited list	No
Weakness	CWE-120
Published	2020-08-04
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: acti

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

Am I affected?

Timeline

2020-08-04 20:15 UTCPublished CVE record published
2026-06-17 02:57 UTCUpdated Record last modified

acti nvr DOWNGRADE

Affected: 2.3.04.07 · 3.0.12.42

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.3.04.07

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.3.04.07 (Debian / Ubuntu)

apt-cache madison nvr sudo apt install nvr=<VERSION_BEFORE_2.3.04.07> sudo apt-mark hold nvr

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

dnf --showduplicates list nvr sudo dnf downgrade nvr-<VERSION_BEFORE_2.3.04.07> sudo dnf versionlock add nvr

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.

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

Exploit-DB: ACTi NVR3 Standard or Professional Server 3.0.12.42 - Denial of Service (PoC)

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-2020-15956?

nvr: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-15956 being exploited?

CVE-2020-15956 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-2020-15956 affect?

CVE-2020-15956 affects nvr. Severity is high (CVSS 7.5). ActiveMediaServer.exe in ACTi NVR3 Standard Server 3.0.12.42 allows remote unauthenticated attackers to trigger a buffer overflow and application termination via a malformed payload.

How urgent is CVE-2020-15956?

Priority 60/100. High severity; EPSS top 3%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

References

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