Security readout for executives and security teams
Plain-English summary
A flaw in RDK-B WebUI can let an unauthenticated remote attacker forge a login token and gain administrator access. Successful abuse could expose or alter device configuration and disrupt service. The supplied record assigns CVSS 9.8, making affected, remotely reachable management interfaces an urgent concern.
Executive priority
Treat as an immediate investigation and exposure-reduction priority. Administrative takeover could affect confidentiality, integrity, and availability. Prioritize internet-reachable or broadly accessible devices, obtain authoritative remediation guidance from RDK or the device vendor, and monitor for suspicious administrative activity.
Technical view
CVE-2026-19505 is an improper cryptographic signature verification flaw (CWE-347) in jst_functions.c. RDK-B WebUI rdkb-2025q4-kirkstone.04.10.26 reportedly accepts a forged JWT with an invalid RSA signature, enabling authentication bypass and administrative access without credentials or user interaction.
Likely exposure
Exposure is highest where the affected RDK-B WebUI build is deployed and reachable from untrusted networks. The bundle identifies the rdkb-2025q4-kirkstone line but specifically describes build 04.10.26; organizations should confirm exact build applicability with RDK guidance. No CPE identifiers are supplied.
Exploitation context
The vulnerability is remotely reachable, low complexity, requires no privileges, and needs no user interaction. The supplied bundle does not identify CISA KEV listing or evidence of active exploitation. Public disclosure exists, so defenders should treat exposed interfaces as time-sensitive without claiming observed exploitation.
Researcher notes
The core failure is acceptance of a JWT whose RSA signature is invalid. The bundle attributes the issue to jst_functions.c and CWE-347. It does not provide CPEs, a confirmed fixed version, named mitigation, or active-exploitation evidence. Exact downstream device and firmware impact therefore requires vendor confirmation.
Mitigation direction
- Inventory devices running RDK-B WebUI and record their exact firmware or WebUI builds.
- Restrict WebUI access to trusted management networks and authenticated administrative paths.
- Remove direct internet exposure and enforce network-level access controls where operationally feasible.
- Check current RDK or device-vendor guidance for an approved fixed release or mitigation.
- Apply vendor-approved updates promptly after compatibility testing.
Validation and detection
- Confirm whether deployed builds match rdkb-2025q4-kirkstone.04.10.26 or vendor-defined affected versions.
- Verify externally that WebUI management endpoints are not reachable from untrusted networks.
- Review authentication and administrative logs for unexpected sessions, token anomalies, or configuration changes.
- Confirm network controls restrict WebUI access to authorized management sources.
- After remediation, verify the installed version against vendor guidance and retest authentication controls safely.
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-347: 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-2026-19505 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
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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
1 official scoreWe 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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H3.95.9CISA-ADPVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- 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
- https://whitehats.pwr.edu.pl//blog/2026-08-19-multiple-vulnerabilities-in-rdkb/CVE reference, certcc
- https://developer.rdkcentral.com/documentation/documentation/rdk_broadband_documentation/components/webui/CVE reference, certcc
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 Verification of Cryptographic Signature
Improper Verification of Cryptographic Signature represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.