Security readout for executives and security teams
Plain-English summary
A remotely reachable flaw in the Tenda AC12 management interface can corrupt memory when processing a reboot-schedule setting. Successful exploitation could compromise the router’s confidentiality, integrity, and availability. The confirmed affected firmware is 15.03.06.23_multi_TD01, and the supplied scoring indicates authentication is required.
Executive priority
Treat confirmed affected devices as urgent, especially where management access crosses trust boundaries. Immediately reduce interface exposure, identify the accountable device owner, and obtain current remediation guidance from Tenda. Replacement should be considered if a supported fixed firmware cannot be confirmed.
Technical view
CVE-2026-19821 is a buffer overflow in formSetRebootTimer within the httpd endpoint /goform/SetSysAutoRebbotCfg. An improperly handled rebootTime argument triggers the issue. It is classified under CWE-119 and CWE-120. The supplied CVSS 2.0 score is 9.0 with complete confidentiality, integrity, and availability impacts.
Likely exposure
Exposure is confirmed only for Tenda AC12 firmware 15.03.06.23_multi_TD01. Devices are at greatest risk when their web management interface is reachable from the internet or untrusted networks. The supplied CVSS vector indicates that authenticated access is required.
Exploitation context
A public technical disclosure and proof-of-concept reference exist, meaning attackers can study the vulnerability. The supplied bundle says exploitation may be possible, but the CVE is not listed in KEV and provides no evidence of active exploitation in the wild.
Researcher notes
The endpoint, vulnerable argument, affected firmware, public disclosure, and memory-corruption class are identified. However, the supplied sources do not establish a vendor patch, reliable compromise indicators, active exploitation, or whether other AC12 firmware versions are affected. Avoid extrapolating beyond the named release.
Mitigation direction
- Block internet and untrusted-network access to the AC12 management interface.
- Restrict management access to authorized administrators on a dedicated trusted network.
- Check Tenda guidance for corrected firmware; no fixed release is identified in the supplied sources.
- Replace or isolate affected devices if no supported fixed firmware is available.
Validation and detection
- Inventory Tenda AC12 devices and record their exact firmware versions.
- Verify whether each management interface is reachable from internet or untrusted network segments.
- Review access logs for requests to /goform/SetSysAutoRebbotCfg and unexplained configuration changes or restarts.
- Confirm management authentication uses authorized accounts and remove unnecessary access.
- After mitigation, verify network restrictions and any vendor-recommended firmware update.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-119: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCWE-120: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-19821 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9 (2.0)
- Known Exploited
- No
- Published
Vector: AV:N/AC:L/Au:S/C:C/I:C/A:C/E:POC/RL:ND/RC:UR
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
SSVC decision data
CVSS vector scores
4 official scoresWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
AV:N/AC:L/Au:S/C:C/I:C/A:C/E:POC/RL:ND/RC:UR810VulDBCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:R2.85.9VulDBCVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:P/RL:X/RC:R2.85.9VulDBCVSS: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——VulDBVulnerability scoring details
Base CVSS 4.0 score
8.7HighVector: 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
Base CVSS 3.1 score
8.8HighVector: 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
Base CVSS 3.0 score
8.8HighVector: 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
Base CVSS 2.0 score
9CriticalVector: AV:N/AC:L/Au:S/C:C/I:C/A:C/E:POC/RL:ND/RC:UR
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- Source timelineVulDB
Advisory disclosed
- Source timelineVulDB
VulDB entry created
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- Source timelineVulDB
VulDB entry last update
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- VDB-389954 | Tenda AC12 httpd web management interface SetSysAutoRebbotCfg formSetRebootTimer buffer overflowCVE reference, VulDB · vdb-entry, technical-description
- VDB-389954 | CTI Indicators (IOB, IOC, IOA)CVE reference, VulDB · signature, permissions-required
- CVE-2026-19821 | CVE Analysis and ReportCVE reference, VulDB · third-party-advisory
- Submit #868922 | Tenda AC12 US_AC1206V1.0RTL_V15.03.06.23_multi_TD01.bin Buffer OverflowCVE reference, VulDB · third-party-advisory
- https://github.com/lipenghai/iot_bug/blob/main/Tenda/AC12/4.mdCVE reference, VulDB · exploit
- https://www.tenda.com.cn/CVE reference, VulDB · product
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Restriction of Operations within the Bounds of a Memory Buffer
Improper Restriction of Operations within the Bounds of a Memory Buffer represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.
Buffer Copy without Checking Size of Input
Buffer Copy without Checking Size of Input represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.