CVE-2025-12611: Tenda AC21 · Buffer Overflow
Affects Tenda AC21Source CVE Database V5
Public exploit available · CVSS 8.7 High.
Data as of 26 Oct 2026, 10:12 UTC
- EPSS
- 0.7% chance of exploitation in 30 days – higher than 54% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:PExploitation evidence
Disclosed: evidence found.
CVE published 3 Nov 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: evidence found.
CVSS exploit maturity: proof of concept public
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), CVSS vector, the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| Tenda AC21 | Affected
| Fixed in– |
AI-suggested
To mitigate CVE-2025-12611, affected users should immediately check for firmware updates from Tenda and apply any patches once available. In the absence of official patches, users should disable the PPTP server functionality if not required, as this is the vulnerable component. Network administrators should implement network-level protections such as firewall rules to restrict access to the router’s management interfaces, especially blocking inbound traffic to the /goform/SetPptpServerCfg endpoint. Employing network segmentation to isolate vulnerable devices can limit the impact of a compromise. Monitoring network traffic for unusual activity targeting the router can help detect exploitation attempts early. Additionally, users should consider replacing affected devices with models from vendors with a stronger security track record if patches are delayed. Regularly auditing router configurations and disabling unnecessary services reduces the attack surface. Finally, educating users about the risks of exposed network devices and encouraging timely updates is critical.
Description
A vulnerability was identified in Tenda AC21 16.03.08.16. This vulnerability affects the function formSetPPTPServer of the file /goform/SetPptpServerCfg. The manipulation of the argument startIp leads to buffer overflow. Remote exploitation of the attack is possible. The exploit is publicly available and might be used.