Amcrest Cameras and NVR Stack-based Buffer Overflow Vulnerability (CVE-2020-5735)
Published In CISA KEV since Sources: CVE.org
What is affected, what to do
Amcrest cameras and NVR are vulnerable to a stack-based buffer overflow over port 37777. An authenticated remote attacker can abuse this issue to crash the device and possibly execute arbitrary code.
The vulnerability is being actively exploited; treat it as a priority. The available sources name no fixed version. Check the vendor guidance in the references below. Immediate actions, mitigation and detection rules are in the runbook below.
- Affected
- Amcrest
eq before 2.623.00AC004.0.R.200316, 2.420.AC00.18.R.20200217, 2.800.00AC000.0.R.200330, 2.800.0000000.6.R.200314.bin, 2.622.00AC000..before 2.623.00AC004.0.R.200316, 2.420.AC00.18.R.20200217, 2.800.00AC000.0.R.200330, 2.800.0000000.6.R.200314.bin, 2.622.00AC000
- Amcrest
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Metrics
8.8
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
8.8
CVSS v3
Severity High on the scale from 0 to 10.
Source: CVE.org
36.2 %
EPSS score
Elevated — model estimates 10-50% exploitation likelihood.
Source: FIRST EPSS, percentile 98.5
Show all metrics
- Severity
- Critical
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 221.60 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- actively exploited
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 8.8 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 8.8
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 36.2 %
- Elevated — model estimates 10-50% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 98.5
- Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- Actively exploited
- Published
In CISA KEV since
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- CISA assessment (SSVC)
- Exploitation: active · not automatable · Technical impact: total
- Source: CISA Vulnrichment, as of 6 February 2025
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-121
Response and mitigation
Why act now?
Prioritisation rationale
This flaw is network-reachable with low attack complexity and can lead to full loss of confidentiality, integrity and availability. Its exploitation likelihood ranks among the highest of all known CVEs. Attackers mass-scan for exposed port 37777 services to crash devices or to take them over for IoT botnets or as a foothold into internal networks. No ransomware use is known. If devices are internet-exposed or not segmented from office or OT networks, treat this as critical (patch or block within 24 h). For KRITIS operators, losing physical-security surveillance is itself a potentially NIS2-reportable incident. Fully isolated devices with no internet path can follow the regular patch cycle.
Runbook step 1
Immediate response (0-24 h)
- Inventory and check exposure: Identify every Amcrest camera and NVR, including devices from other vendors built on the same firmware base. Then scan internally and externally for open TCP 37777, e.g.
nmap -p 37777 --open <subnet>. Add Shodan/Censys queries against your public IP ranges. Treat any internet-reachable device as potentially compromised. - Block port 37777 at the perimeter now: Drop inbound TCP 37777 at firewalls and routers. Remove port forwards and UPnP mappings for cameras and NVRs. Disable the P2P/cloud remote-access feature unless it is strictly required.
- Update firmware:
- IP2M-841 to v2.420.AC00.18.R.20200217
- IP2M-841-v3 to v2.800.0000000.6.R.200314
- IP2M-853EW, IP2M-858W and IP2M-866EW to v2.623.00AC004.0.R.200316
- Other affected lines per the advisory: 2.800.00AC000.0.R.200330 or 2.622.00AC000.
- For the 1080-Lite 8CH and AMDV10814-H5 NVRs, a patch is available from the vendor — check the vendor advisory for the exact version.
- Rotate credentials: NVD says low-privilege authentication is required, while CISA describes the attack as unauthenticated. Either way, set unique, strong passwords on all device and NVR accounts. Disable default and guest accounts and delete unused users.
- Isolate suspect devices: Pull exposed devices showing unexplained reboots or odd outbound traffic. Reflash them from a vendor image and factory-reset them rather than just upgrading in place.
- Inventory and check exposure: Identify every Amcrest camera and NVR, including devices from other vendors built on the same firmware base. Then scan internally and externally for open TCP 37777, e.g.
Runbook step 2
Mitigation layers
- Network segmentation: Move cameras and NVRs into a dedicated CCTV VLAN with no internet access. Permit TCP 37777 only from within that VLAN or from the VMS server, e.g.
permit tcp host <VMS-IP> <CCTV-net> eq 37777; deny tcp any <CCTV-net> eq 37777 log. - Egress filtering: Default-deny outbound traffic from the CCTV VLAN. Allow only NTP and update servers where needed. This stops payload staging and botnet C2 after successful code execution.
- IPS rule: Deploy a Suricata/Snort rule for TCP 37777 from unauthorised sources, plus an alert on unusually large single packets (overflow payload), e.g.
alert tcp !$VMS_HOSTS any -> $CCTV_NET 37777 (msg:"CVE-2020-5735 Amcrest 37777 access"; flow:to_server,established; dsize:>1024; sid:9000001;). Tune the threshold against baseline traffic. - Remote access: Allow remote viewing only via VPN with MFA, never via direct port exposure. Turn P2P off permanently.
- Configuration hardening: Disable Telnet, SSH, UPnP, ONVIF and any unused services. Restrict the web UI to HTTPS from the management network only.
- Lifecycle: Schedule replacement for any device that cannot be updated. Until then, fully isolate it from corporate and OT networks.
- Network segmentation: Move cameras and NVRs into a dedicated CCTV VLAN with no internet access. Permit TCP 37777 only from within that VLAN or from the VMS server, e.g.
Runbook step 3
Detection rules
- Zeek conn.log / firewall logs: Connections to port 37777 from sources outside the VMS allowlist, e.g. SPL
index=fw dest_port=37777 NOT src_ip IN (<VMS-IPs>) | stats count by src_ip, dest_ip. Any hit from the internet is critical. - Availability monitoring: Unexpected camera or NVR reboots and crashes (syslog boot messages, ICMP/SNMP outages, VMS stream drops). Correlate them in time with inbound 37777 traffic — this is the classic signature of failed exploit attempts.
- Outbound anomalies (Zeek/NetFlow): Cameras contacting new external destinations, pulling files via HTTP/TFTP, or using unusual ports (IRC, Telnet 23/2323, high ports). Sigma shape:
src_ip|cidr: <CCTV-net> AND NOT dst_ip|cidr: <allowed-destinations>. - Scan detection: IDS alerts for horizontal scans of TCP 37777 or 37777–37778 inside the network. These scans indicate lateral spread from an already compromised device.
- Authentication events: Failed and successful logins in device/NVR logs (where forwarded via syslog). Bursts of failures followed by a 37777 session are a strong signal.
- Zeek conn.log / firewall logs: Connections to port 37777 from sources outside the VMS allowlist, e.g. SPL
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
Amcrest cameras and NVR are vulnerable to a stack-based buffer overflow over port 37777. An authenticated remote attacker can abuse this issue to crash the device and possibly execute arbitrary code.
Source: NVD (NIST), cvelistv5, CISA KEV Catalog
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| — | Amcrest |
|
|
Vendors and products
Affected operating systems
| Other | amcrest | 1080-lite_8ch_firmware | — |
| Other | amcrest | amdv10814-h5_firmware | — |
| Other | amcrest | ip2m-841-v3_firmware | — |
| Other | amcrest | ip2m-841_firmware | — |
| Other | amcrest | ip2m-853ew_firmware | — |
| Other | amcrest | ip2m-858w_firmware | — |
| Other | amcrest | ip2m-866ew_firmware | — |
| Other | amcrest | ip2m-866w_firmware | — |
| Other | amcrest | ip4m-1053ew_firmware | — |
| Other | amcrest | ip8m-2454ew_firmware | — |
| Other | amcrest | ip8m-2493eb_firmware | — |
| Other | amcrest | ip8m-2496eb_firmware | — |
| Other | amcrest | ip8m-2597e_firmware | — |
| Other | amcrest | ip8m-mb2546ew_firmware | — |
| Other | amcrest | ip8m-mt2544ew_firmware | — |
| Other | amcrest | ip8m-t2499ew_firmware | — |
| Other | amcrest | ipm-721_firmware | — |
| Other | amcrest | ipm-hx1_firmware | — |
Weakness classes (CWE)
CWE-121Stack-based Buffer Overflow
Variant
A stack-based buffer overflow condition is a condition where the buffer being overwritten is allocated on the stack (i.e., is a local variable or, rarely, a parameter to a function).
Entry at MITRE CWE-121
Public exploit references
Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.
| CISA KEV Catalog | CISA Known Exploited Vulnerability (opens in a new tab)cisa.gov | actively exploited | |
| Packet Storm | Amcrest Dahua NVR Camera IP2M 841 Denial Of Service (opens in a new tab)packetstormsecurity.com | PoC (publicly reported)reported, not verified | — |
References & sources
- tenable.comsecurity/research/tra-2020-20x_refsource_MISC, Third-party advisory
- packetstormsecurity.comfiles/157164/Amcrest-Dahua-NVR-Camera-IP2M-841-Denial-Of-Servic…x_refsource_MISC, Exploit, Third-party advisory, Vulnerability database
- cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2020-5735government-resource, US government resource
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