Vulnerability · Published Aug 19, 2026 · Assigned by certcc
CVE-2026-19505RDK-B WebUI improper cryptographic signature verification vulnerability
Critical 9.8
In plain English
A critical-severity security flaw in RDK-B WebUI from RDK. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 44% of all known vulnerabilities).
Severity (CVSS 3.1)9.8Critical
Exploit odds (30 days)0.5%top 56.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Improper cryptographic signature verification in `jst_functions.c` in RDK-B WebUI `rdkb-2025q4-kirkstone.04.10.26` allows a remote attacker to bypass authentication and obtain administrative access via a forged JWT containing an invalid RSA signature.
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| RDK | RDK-B WebUI | rdkb-2025q4-kirkstone |
Weakness: CWE-347 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H