Security readout for executives and security teams
Plain-English summary
A flaw in one identified Tenda W20E firmware build can let an authenticated remote user corrupt device memory through the QoS editing interface. The reported impact includes complete loss of confidentiality, integrity, and availability. A public proof of concept increases near-term risk, although active exploitation has not been established.
Executive priority
Treat this as an urgent device-management risk. Locate affected W20E appliances, isolate their administrative interfaces, and seek vendor remediation promptly. Public proof-of-concept availability justifies accelerated action, but current evidence does not support claiming ongoing attacks.
Technical view
CVE-2026-19822 is a stack-based buffer overflow in lstAdd within /goform/editQos. Manipulating qosListConnecttedNum reportedly triggers the flaw remotely with authentication. It affects Tenda W20E firmware 15.11.0.6(1068_1546_841)_CN_TDC and is classified as CWE-119 and CWE-121. The supplied CVSS 2.0 score is 9.0.
Likely exposure
Exposure is most likely where the exact affected W20E firmware is deployed and its authenticated management or QoS interface is reachable remotely. Risk is greater when management access is available from untrusted networks. The supplied evidence does not establish whether other firmware builds or Tenda products are affected.
Exploitation context
A public proof of concept is referenced, lowering the barrier to vulnerability research and potential attacks. However, the supplied bundle marks the CVE as absent from KEV and provides no evidence of active exploitation. The CVSS vector indicates that authenticated access is required.
Researcher notes
The record identifies qosListConnecttedNum as the trigger argument and lstAdd as the affected function. CVSS 2.0 metrics indicate network reachability, low complexity, single authentication, proof-of-concept availability, and potentially complete impact. Root-cause depth, execution reliability, affected-version breadth, and a vendor-confirmed fix remain undocumented in the supplied evidence.
Mitigation direction
- Inventory Tenda W20E devices and identify those running the exact affected firmware build.
- Restrict management access to trusted administrative networks or a controlled VPN.
- Prevent untrusted users from reaching the device management and QoS interfaces.
- Check Tenda guidance for corrected firmware or vendor-approved mitigations; no patch is identified in the supplied sources.
- Disable affected QoS administration temporarily if operationally acceptable and supported by the device.
Validation and detection
- Confirm each W20E firmware version through trusted inventory or its administrative interface.
- Review network controls governing access to the device management interface.
- Identify accounts permitted to change QoS settings and remove unnecessary access.
- Monitor device logs and availability for unusual QoS changes, crashes, or restarts.
- Verify any vendor-provided firmware against Tenda's published release information before deployment.
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-121: 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-2026-19822 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-389955 | Tenda W20E QoS Edit editQos lstAdd stack-based overflowCVE reference, VulDB · vdb-entry, technical-description
- VDB-389955 | CTI Indicators (IOB, IOC, IOA)CVE reference, VulDB · signature, permissions-required
- CVE-2026-19822 | CVE Analysis and ReportCVE reference, VulDB · third-party-advisory
- Submit #869006 | Tenda W20E US_W20EV4.0br_V15.11.0.6(1068_1546_841)_CN_TDC.bin Buffer OverflowCVE reference, VulDB · third-party-advisory
- https://github.com/paueger/mycve/blob/main/Tenda_W20E/3.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.
Stack-based Buffer Overflow
Stack-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.