cbcvebase.
CVE-2025-8810
published 2025-08-10

CVE-2025-8810: A vulnerability classified as critical was found in Tenda AC20 16.03.08.05. Affected by this vulnerability is the function strcpy of the file…

PriorityP268high8.8CVSS 3.1
AVNACLPRLUINSUCHIHAH
EPSS
1.04%
60.0th percentile
A vulnerability classified as critical was found in Tenda AC20 16.03.08.05. Affected by this vulnerability is the function strcpy of the file /goform/SetFirewallCfg. The manipulation of the argument firewallEn leads to stack-based buffer overflow. The attack can be launched remotely. The exploit has been disclosed to the public and may be used.

Affected

2 ranges
VendorProductVersion rangeFixed in
tendaac20——
tendaac20_firmware——

Detection & IOCsextracted from sources · hover to see the quote

url/goform/SetFirewallCfg↗
path/goform/SetFirewallCfg↗
snort
alert http any any -> $HOME_NET any (msg:"ET WEB_SPECIFIC_APPS Tenda SetFirewallCfg firewallEn Parameter Buffer Overflow Attempt (CVE-2025-8810, CVE-2025-29358, CVE-2025-1851, CVE-2024-2809)"; flow:established,to_server; http.method; content:"POST"; http.uri; bsize:22; content:"/goform/SetFirewallCfg"; fast_pattern; http.request_body; content:"firewallEn|3d|"; pcre:"/^[^&]{100,}(?:&|$)/R"; reference:cve,2025-8810; reference:url,www.cve.org/CVERecord/SearchResults?query=SetFirewallCfg; reference:cve,2025-1851; reference:cve,2025-29358; reference:url,github.com/peris-navince/founded-0-days/blob/main/Tenda/ac8/formSetFirewallCfg/1.md; reference:cve,2024-2809; classtype:web-application-attack; sid:2065155; rev:1; metadata:affected_product Tenda, attack_target Networking_Equipment, tls_state plaintext, created_at 2025_10_10, cve CVE_2025_1851_CVE_2025_8810_CVE_2024_2809_CVE_2025_29358, deployment Perimeter, deployment Internal, performance_impact Low, confidence High, signature_severity Major, tag Exploit, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2025_10_10, mitre_tactic_id TA0001, mitre_tactic_name Initial_Access, mitre_technique_id T1190, mitre_technique_name Exploit_Public_Facing_Application; target:dest_ip;)
bytes
firewallEn=<100+ chars>
  • →Exploit arrives as an HTTP POST request to /goform/SetFirewallCfg with the firewallEn parameter value exceeding 100 characters (URL-encoded '=' = '|3d|'), indicating a stack-based buffer overflow attempt.
  • →The URI /goform/SetFirewallCfg is exactly 22 bytes; use a strict URI length match (bsize:22) to reduce false positives.
  • →Attack is plaintext HTTP only (tls_state plaintext); monitor perimeter and internal HTTP traffic to Tenda networking equipment.
  • →MITRE ATT&CK mapping: TA0001 Initial Access / T1190 Exploit Public-Facing Application.
  • →Public exploit PoC is available on GitHub for the related SetFirewallCfg vulnerability family.
  • ·The Snort/Suricata rule (sid:2065155) covers four CVEs simultaneously (CVE-2025-8810, CVE-2025-29358, CVE-2025-1851, CVE-2024-2809); a true positive may relate to any of these, not exclusively CVE-2025-8810.
  • ·The overflow threshold in the detection rule is set at 100 characters for the firewallEn value; legitimate values should be far shorter, but tuning may be needed in environments with unusual firewall configurations.

CVSS provenance

nvdv3.18.8HIGHCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
nvdv4.07.4HIGHCVSS: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
nvdv2.09.0CRITICALAV:N/AC:L/Au:S/C:C/I:C/A:C
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