Tenda AC11 Router Stack Buffer Overflow Vulnerability
Tenda AC11 devices contain a stack buffer overflow vulnerability in /goform/setmac which allows attackers to execute code via a crafted post request.
- Vendor
- Tenda
- Product
- AC11 Router
- CVSS
- 9.8
- EPSS (exploit probability)
- 86.5%
- Status
- kev
- CISA patch-by (BOD 22-01)
- Added to KEV
Is CVE-2021-31755 being exploited?
Yes. CISA added CVE-2021-31755 to its Known Exploited Vulnerabilities catalog on . CISA only lists a CVE when it has reliable evidence of exploitation in the wild.
FIRST's EPSS model puts the probability of exploitation activity in the next 30 days at 86.5% (scored October 14, 2026).
- CISA KEV[ LISTED ]
- ENISA EUVD (exploited)[ — ]
- CIRCL KEV[ — ]
Catalog snapshot 2026-11-13. Full cross-catalog view: /kev-comparison
CVE-2021-31755 timeline
Every event links to its source. Catalog dates are each catalog's own; day offsets count from NVD publication. Data: JSON
What to do
CISA required actionApply updates per vendor instructions.
US federal civilian agencies must remediate by (14 days after listing) under BOD 22-01. Everyone else: that deadline is a sensible upper bound, not a target. Vendor guidance and the NVD record are linked under Source above.
Other Tenda CVEs we track
| CVE / Vulnerability | Severity | CVSS | EPSS | Added to KEV |
|---|---|---|---|---|
| CVE-2026-11405 Tenda router firmware undocumented authentication backdoorwrite-up | [ HIGH ] | — | 0.8% | — |
| CVE-2020-10987 Tenda AC1900 Router AC15 Model Remote Code Execution Vulnerability | [ CRITICAL ] | 9.8 | 79.8% | |
| CVE-2018-14558 Tenda AC7, AC9, and AC10 Routers Command Injection Vulnerability | [ CRITICAL ] | 9.8 | 8.5% |