Security readout for executives and security teams
Plain-English summary
A flaw in one TOTOLINK A800R firmware release can let an authenticated remote user overflow router memory through its management interface. Successful exploitation could compromise confidentiality, integrity, and availability. Public proof-of-concept material raises near-term risk, but the supplied sources do not establish active exploitation or identify a vendor fix.
Executive priority
Treat as an urgent network-edge exposure review. Locate affected routers immediately, reduce management access, and seek vendor-supported remediation. Prioritize externally manageable devices, while recognizing that public proof-of-concept availability is not evidence of active exploitation.
Technical view
CVE-2026-19846 is a stack-based buffer overflow in firewall.so's setUrlFilterRules function, reached through /cgi-bin/cstecgi.cgi when processing the url argument. The listed CVSS 2.0 vector scores 9.0 and indicates network reachability, low complexity, required authentication, and potentially complete confidentiality, integrity, and availability impact.
Likely exposure
Confirmed scope is limited to TOTOLINK A800R firmware 4.1.2cu.5137_B20200730. Risk is greatest where the management CGI endpoint is reachable by untrusted or compromised authenticated users. The bundle does not establish whether other versions are affected or whether internet exposure is enabled by default.
Exploitation context
A public proof of concept is referenced, and remote initiation is reported. The CVSS vector indicates authentication is required. The CVE is not listed as KEV in the supplied bundle, and no cited evidence confirms exploitation in the wild.
Researcher notes
CWE-119 and CWE-121 classifications support an improper memory-boundary and stack-overflow finding. Available details identify the function, CGI path, argument, and exact firmware, but do not document vendor patch status, affected-version range, default exposure, observed attacks, or reliable indicators of compromise.
Mitigation direction
- Identify A800R devices running firmware 4.1.2cu.5137_B20200730.
- Restrict management-interface access to trusted administrative networks and users.
- Disable unnecessary remote management exposure where operationally feasible.
- Review TOTOLINK guidance for an approved firmware update or mitigation.
- Isolate or replace affected devices if no supported remediation is available.
Validation and detection
- Confirm device model and exact installed firmware version.
- Determine whether /cgi-bin/cstecgi.cgi is reachable from untrusted networks.
- Review management accounts and revoke unnecessary or compromised credentials.
- Check device logs for unusual authenticated configuration activity or instability.
- Verify remediation status against current TOTOLINK guidance without using public exploit material.
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-2026-19846 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-389982 | TOTOLINK A800R firewall.so cstecgi.cgi setUrlFilterRules stack-based overflowCVE reference, VulDB · vdb-entry, technical-description
- VDB-389982 | CTI Indicators (IOB, IOC, IOA)CVE reference, VulDB · signature, permissions-required
- CVE-2026-19846 | CVE Analysis and ReportCVE reference, VulDB · third-party-advisory
- Submit #869456 | Totolink A800R V4.1.2cu.5137_B20200730 Buffer OverflowCVE reference, VulDB · third-party-advisory
- https://github.com/panda666-888/vuls/blob/main/totolink/a800r/setUrlFilterRules.mdCVE reference, VulDB · exploit
- https://www.totolink.net/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.