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CVE-2026-9428 Tenda CVE debrief

A stack-based buffer overflow vulnerability exists in the Tenda F1202 router firmware version 1.2.0.20(408). The vulnerability is located in the `fromPPTPUserSetting` function within the `/goform/PPTPUserSetting` endpoint. Remote attackers can exploit this by manipulating the `delno` argument to trigger memory corruption. The CVSS 4.0 score of 7.4 (HIGH) reflects network attack vector, low attack complexity, and required privileges, with high impacts to confidentiality, integrity, and availability. The exploit has been publicly disclosed, increasing the risk of active exploitation. The CVE was published on 2026-05-25 and last modified on 2026-05-26.

Vendor
Tenda
Product
F1202
CVSS
HIGH 7.4
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-25
Original CVE updated
2026-07-23
Advisory published
2026-05-25
Advisory updated
2026-07-23

Who should care

Network administrators managing Tenda F1202 deployments, SOHO network operators, MSSPs monitoring consumer-grade router vulnerabilities, and security teams responsible for edge network device hardening

Technical summary

The vulnerability resides in the `fromPPTPUserSetting` function handling HTTP POST requests to `/goform/PPTPUserSetting`. Insufficient bounds checking on the `delno` parameter allows attacker-controlled data to overflow stack-allocated buffers. Successful exploitation may result in arbitrary code execution with elevated privileges on the router's embedded system. The attack requires network access and valid credentials (PR:L per CVSS vector), though the public exploit availability suggests weaponization risk.

Defensive priority

HIGH

Recommended defensive actions

  • Restrict network access to Tenda F1202 router administrative interfaces, particularly the /goform/PPTPUserSetting endpoint
  • Apply firmware updates from Tenda if available; monitor vendor security advisories at official Tenda channels
  • Implement network segmentation to isolate affected routers from untrusted networks
  • Consider disabling PPTP VPN functionality if not required for business operations
  • Monitor for suspicious requests to /goform/PPTPUserSetting with anomalous delno parameter values
  • Review logs for signs of exploitation attempts targeting the fromPPTPUserSetting function

Evidence notes

Vulnerability identified through Vuldb submission 813911. CWE-121 (Stack-based Buffer Overflow) and CWE-119 (Improper Restriction of Operations within the Bounds of a Memory Buffer) assigned. CVSS 4.0 vector: AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/E:P.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-9428 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-9428

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-9428 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-9428

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.