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Fencer Intel
high 8.8

CVE-2025-8939 json

Tenda AC20 WifiGuestSet buffer overflow

published last yr. modified 4mo ago also EUVD-2025-24671

cvss
8.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.0%
EPSS 1.0% chance of exploitation in 30 days, percentile 63%
public exploits
0
none known

Summary

A vulnerability was determined in Tenda AC20 up to 16.03.08.12. Affected is an unknown function of the file /goform/WifiGuestSet. The manipulation of the argument shareSpeed leads to buffer overflow. It is possible to launch the attack remotely. The exploit has been disclosed to the public and may be used.

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CISA SSVC

Exploitation
Proof of concept is public
Automatable
no
Technical impact
total
Assessed
last yr.

Exploit prediction

1.03% chance of exploitation in the next 30 days, higher than 63% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • github.com https://github.com/lin-3-start/lin-cve/blob/main/Tenda%20AC20/Tenda%20AC20.md referenced PoC, tagged "exploit" by a source, unverified
  • github.com https://github.com/lin-3-start/lin-cve/blob/main/Tenda%20AC20/Tenda%20AC20.md#3-poc referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 8.7 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:P
CNA 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:R
CNA 3.0 8.8 CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:R
CNA 2.0 9.0 AV:N/AC:L/Au:S/C:C/I:C/A:C/E:POC/RL:ND/RC:UR
CNA 4.0 7.4 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:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
CNA 3.1 8.8 CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CNA 2.0 9.0 AV:N/AC:L/Au:S/C:C/I:C/A:C

Affected products

  • Tenda AC20

Classification

Weakness
  • CWE-120 Buffer Copy without Checking Size of Input
  • CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.