What is CVE-2026-19821?

CVE-2026-19821 is Tenda AC12 httpd web management interface SetSysAutoRebbotCfg formSetRebootTimer buffer overflow. The supplied enrichment data classifies it as Remote Code Exec mapped to CWE-120 CWE-120; CWE-119 CWE-119.

Which versions are affected?

Affected product and version evidence is listed in the product table above. Current public advisories should be checked for exact version scope before patch targeting is finalized.

Is there active exploitation?

Active exploitation is not confirmed from current sources for CVE-2026-19821. If exploitation is not confirmed from current sources, teams should document that status and continue monitoring KEV, vendor, and telemetry updates.

No. CVE-2026-19821 is not listed in CISA KEV in the supplied enrichment data. KEV status should be monitored because it can change after initial disclosure or after exploitation becomes publicly confirmed.

Is there a public exploit?

3 public PoC repositories reported; 0 marked weaponized in current dataset. Public exploit or PoC availability should raise triage priority, especially for exposed or business-critical systems.

How can defenders detect it?

Start with web/proxy/WAF logs, application logs, network IDS/IPS, EDR process telemetry, host service logs where available. Look for vulnerability-class behavior, product errors, suspicious authentication events, exploit probes, and abnormal process activity based only on evidence that applies to the affected product.

How should teams prioritize it?

Prioritize CVE-2026-19821 using CVSS 8.8, EPSS 0%, KEV status, public PoC status, and asset exposure. Internet-facing, privileged, or business-critical deployments should be handled first.

Are workarounds available?

The supplied mitigation guidance says to apply vendor patches and restrict external exposure until fixed. Fixed-version evidence is listed in the mitigation section above.

Which threat actors are linked publicly?

No public threat actor linkage is confirmed from current sources. Do not attribute exploitation to a threat actor unless the source evidence explicitly supports that linkage.

What should be done in the next 24 hours?

Identify exposed assets running affected vendor/product/version combinations. Prioritize based on EPSS, PoC availability, and external exposure. Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class. Open remediation tickets with affected assets, owners, evidence status, and detection coverage so decisions are traceable.

highRemote Code Execpublic exploit

CVE-2026-19821

CVE-2026-19821 — Tenda AC12 httpd web management interface SetSysAutoRebbotCfg formSetRebootTimer buffer overflow

A vulnerability was determined in Tenda AC12 15.03.06.23_multi_TD01. This vulnerability affects the function formSetRebootTimer of the file /goform/SetSysAutoRebbotCfg of the component httpd web management interface. This manipulation of the argument rebootTime causes buffer overflow. The attack may be initiated remotely. The exploit has been publicly disclosed and may be utilized.

Published Aug 14, 2026Updated Aug 14, 2026Sources: NVD, Tenda (CNA), GitHub, SOCRadar CTI

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the scoring sources call it.

Exploitation

Exploit code

public exploit, none observed

EPSS

ahead of 0% of scored CVEs

Affects

Tenda

AC12

CVSS base

8.8

high · 6 sources

Remediation

The vendor's own words where we have them.

Upgrade AC12 to a fixed release. Apply vendor patches per advisory and restrict external exposure of the affected component until patched.

First 24 hours

Ordered from the record's own fields — exposure first, because you cannot patch what you have not found.

Identify exposed assets running affected vendor/product/version combinations.
Prioritize based on EPSS, PoC availability, and external exposure.
Search available logs for exploit probes, errors, authentication anomalies, or suspicious child processes matching the vulnerability class.

Affected scope

Vendor, product and version as the advisories word them.

Vendor	Product	Versions	Status
Tenda	AC12	15.03.06.23_multi_TD01	Vulnerable

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Availability

High

Confidentiality

High

Integrity

High

Scope

Unchanged

Attack Complexity

Low

Attack Vector

Network

Privileges Req

Low

User Interaction

None

Every base score collected

Sources score independently and disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Source
8.8	CVSS 3.1	high	2.8	5.9	NVD
9	CVSS 2.0	high	8	10	vuldb.com (CNA)
8.7	CVSS 4.0	high	—	—	Tenda (CNA)
8.8	CVSS 3.1	high	—	—	Tenda (CNA)
8.8	CVSS 3.0	high	—	—	Tenda (CNA)
9	CVSS 2.0	critical	—	—	Tenda (CNA)

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

What this weakness leads to

MITRE's own consequences and mitigations for the weakness class — the authority's wording, not guidance derived from the CVSS vector.

MITRE

CWE-120 · Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

Modify Memory
Execute Unauthorized Code or Commands
DoS: Crash, Exit, or Restart
DoS: Resource Consumption (CPU)

Mitigation: Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.

CWE-119 · Improper Restriction of Operations within the Bounds of a Memory Buffer

Execute Unauthorized Code or Commands
Modify Memory
Read Memory
DoS: Crash, Exit, or Restart

Weakness & attack patterns

CWE-120
CWE-119

Attack patterns reported against this CVE. The ATT&CK techniques below are inferred from its weakness class.

CAPEC-10 · Buffer Overflow via Environment VariablesCAPEC-100 · Overflow BuffersCAPEC-123 · Buffer ManipulationCAPEC-14 · Client-side Injection-induced Buffer OverflowCAPEC-24 · Filter Failure through Buffer OverflowCAPEC-42 · MIME ConversionCAPEC-44 · Overflow Binary Resource FileCAPEC-45 · Buffer Overflow via Symbolic LinksCAPEC-46 · Overflow Variables and TagsCAPEC-47 · Buffer Overflow via Parameter ExpansionCAPEC-8 · Buffer Overflow in an API CallCAPEC-9 · Buffer Overflow in Local Command-Line Utilities

Public exploit

Capability, not use: code existing is a different claim from anyone running it.

Repositories

Detection

Read off the CVSS vector and the weakness class. Starting points, not rules we have tested.

Search application, proxy, and WAF logs for requests touching /goform/SetSysAutoRebbotCfg.
Prioritize edge telemetry for network-reachable AC12.
Monitor for scanner or exploit-pattern traffic after 3 public PoC repositories were reported.

web/proxy/WAF logsapplication logsnetwork IDS/IPSEDR process telemetryhost service logs

Timeline

What happened to this CVE, newest first — with the readings a source repeats on a schedule counted underneath rather than listed.

2026
Added · CVSS 3.1 8.8 (AV:N)
Aug 14, 2026 · NVD
Initial · CVE published
Aug 14, 2026 · NVD
Reported · Advisory disclosed
Aug 14, 2026 · Tenda
Reported · VulDB entry created
Aug 14, 2026 · Tenda
Reported · VulDB entry last update
Aug 14, 2026 · Tenda
CVE published by mitre
Aug 14, 2026 · SOCRadar CTI

Source activity

Readings a source repeats on a schedule, counted rather than listed.

1×CVE modified by NIST, Cweid, Modified, LinkAug 14, 2026 · SOCRadar CTI

References

6 on the record

github.com/lipenghai/iot_bug/blob/main/Tenda/AC12/4.md
Exploit, Third Party Advisory, NIST
vuldb.com/cve/CVE-2026-19821
Vendor Advisory
vuldb.com/submit/868922
Vendor Advisory
vuldb.com/vuln/389954
Vendor Advisory
vuldb.com/vuln/389954/cti
Vendor Advisory
www.tenda.com.cn/
Vendor Advisory, NIST

Elsewhere on this site

Tendaevery CVE for this vendor
Remote Code Execsame class
CWE-120other pages naming this weakness

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record1

What should defenders know first?

CVE-2026-19821 is Tenda AC12 httpd web management interface SetSysAutoRebbotCfg formSetRebootTimer buffer overflow, a high vulnerability affecting AC12 from Tenda. The current evidence does not list it in CISA KEV, and the exploit status is: Active exploitation is not confirmed from current sources for CVE-2026-19821. Public exploit evidence is: 3 public PoC repositories reported; 0 marked weaponized in current dataset. The affected-version evidence is listed in the key facts and affected products tables. Defenders should first verify whether exposed or business-critical assets run those versions, then apply vendor patches or mitigations, restrict reachable attack surface, and preserve logs for detection review. CVSS 8.8 describes technical severity, while EPSS 0% helps estimate near-term exploit likelihood; neither replaces asset context. Unknown fields should remain explicit in tickets, and threat actor, IOC, victimology, or payload claims should not be added unless a cited source supports them. Monitor CISA KEV, vendor advisories, NVD changes, public PoC repositories, and internal telemetry for update triggers.