What is the CVSS score of CVE-2026-36779?

CVE-2026-36779 has a CVSS 3.1 base score of 7.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. EPSS exploitation probability: 0.0%.

Which versions of Tenda O3 Router are affected by CVE-2026-36779?

Tenda O3 wireless routers running affected firmware versions are exposed to unauthenticated remote denial-of-service attacks that crash devices, potentially disrupting network operations across…

How to fix or mitigate CVE-2026-36779?

Within 24 hours: Conduct inventory of Tenda O3 devices in production, prioritizing critical network segments and documenting firmware versions. Within 7 days: Implement firewall and network segmentation controls restricting HTTP access to router management interfaces; enable logging to detect exploitation attempts. Within 30 days: Monitor Tenda security advisories for patch release; upon availability, develop and schedule deployment plan; if patch remains unavailable, evaluate device replacement with alternatives from vendors maintaining active security support.

Tenda O3 Router CVE-2026-36779

HIGH

Stack-based Buffer Overflow (CWE-121)

2026-06-09 mitre

Buffer Overflow Denial Of Service Stack Overflow Tenda N A

7.5

CVSS 3.1 · Vendor: mitre

Severity by source

Vendor (mitre) PRIMARY

7.5 HIGH

AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Primary rating from Vendor (mitre) · only source for this CVE.

CVSS VectorVendor: mitre

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

None

Availability

High

Lifecycle Timeline

Analysis Generated

Jun 10, 2026 - 19:23 vuln.today

CVSS changed

Jun 10, 2026 - 19:22 NVD

7.5 (HIGH)

CVE Published

Jun 09, 2026 - 00:00 nvd

UNKNOWN (no severity yet)

DescriptionCVE.org

Shenzhen Tenda Technology Co., Ltd Tenda O3 Wireless Router v1.0.0.5(4180) was discovered to contain multiple stack overflows in the fromVirtualSer function via the puVar2, puVar1, __s2, __s1_00, and puVar3 parameters. These vulnerabilities allow attackers to cause a Denial of Service (DoS) via a crafted HTTP request.

AnalysisAI

Denial of service in Tenda O3 Wireless Router firmware v1.0.0.5(4180) allows remote unauthenticated attackers to crash the device by sending crafted HTTP requests that trigger stack buffer overflows in the fromVirtualSer function. Five distinct overflow sinks (puVar2, puVar1, __s2, __s1_00, puVar3) are reachable via the same handler. No public exploit identified at time of analysis, and EPSS rates exploitation likelihood at 0.01%, but a research repository with vulnerability artifacts is referenced.

Technical ContextAI

The Tenda O3 is a SOHO/outdoor wireless router whose web-based management interface exposes a CGI-style handler named fromVirtualSer, typically responsible for processing virtual server (port-forwarding) configuration submissions. The flaw is classified as CWE-121 (Stack-based Buffer Overflow), meaning user-supplied HTTP parameters are copied into fixed-size stack buffers without adequate length validation - likely via unbounded strcpy/sprintf-style operations on the listed variables. On embedded MIPS/ARM routers running stripped-down Linux without modern stack protections (canaries, ASLR, NX often partial), such overflows reliably corrupt the saved return address and crash the httpd daemon. The CPE entry is generic ('n/a'), so authoritative product enumeration must come from the description rather than NVD CPE matching.

RemediationAI

No vendor-released patch identified at time of analysis - the only reference is a third-party GitHub research repository (https://github.com/xhh0124/SemVulLLM/tree/main/O3/fromVirtualSer), not a Tenda advisory. Until Tenda publishes updated firmware for the O3, restrict access to the device's web management interface by disabling remote/WAN-side administration (this prevents internet-borne exploitation but does not block LAN/WLAN attackers and may inconvenience admins managing remote sites), placing the management VLAN behind an ACL that only permits trusted administrative hosts, and blocking inbound HTTP/HTTPS to the router's WAN IP at any upstream firewall. Monitor Tenda's support portal for firmware later than v1.0.0.5(4180) and apply it once released; given Tenda's history with SOHO router vulnerabilities, consider replacing end-of-life O3 units with actively maintained hardware if no patch materializes.