Zyxel VMG4005-B50B up to 5.13(ABRL.5.4)C0 UPnP AddPortMapping buffer overflow

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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6.5$5k-$25k0.00

Summaryinfo

A vulnerability marked as critical has been reported in Zyxel VMG4005-B50B up to 5.13(ABRL.5.4)C0. The affected element is the function AddPortMapping of the component UPnP. Performing a manipulation results in buffer overflow. This vulnerability is identified as CVE-2026-3870. The attack can only be performed from the local network. There is not any exploit available.

Detailsinfo

A vulnerability was found in Zyxel VMG4005-B50B up to 5.13(ABRL.5.4)C0. It has been classified as critical. This affects the function AddPortMapping of the component UPnP. The manipulation with an unknown input leads to a buffer overflow vulnerability. CWE is classifying the issue as CWE-120. The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow. This is going to have an impact on availability. The summary by CVE is:

A buffer overflow vulnerability in the UPnP AddPortMapping() command in Zyxel VMG4005-B50B firmware versions through 5.13(ABRL.5.4)C0 could allow an adjacent attacker to trigger a temporary denial-of-service (DoS) condition affecting the UPnP function of the affected device.

It is possible to read the advisory at zyxel.com. This vulnerability is uniquely identified as CVE-2026-3870 since 03/10/2026. The exploitability is told to be easy. The attack needs to be initiated within the local network. No form of authentication is needed for exploitation. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 06/02/2026).

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

Vendor

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Version

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.5
VulDB Meta Temp Score: 6.5

VulDB Base Score: 6.5
VulDB Temp Score: 6.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 6.5
CNA Vector (Zyxel): 🔒

CVSSv2info

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Buffer overflow
CWE: CWE-120 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Partially

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: no mitigation known
Status: 🔍

0-Day Time: 🔒

Timelineinfo

03/10/2026 CVE reserved
06/02/2026 +83 days Advisory disclosed
06/02/2026 +0 days VulDB entry created
06/02/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: zyxel.com

Advisory: zyxel.com
Status: Confirmed

CVE: CVE-2026-3870 (🔒)
GCVE (CVE): GCVE-0-2026-3870
GCVE (VulDB): GCVE-100-367791

Entryinfo

Created: 06/02/2026 08:07
Changes: 06/02/2026 08:07 (63)
Complete: 🔍
Cache ID: 216::103

Be aware that VulDB is the high quality source for vulnerability data.

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