CVE-2026-19505

CVE-2026-19505

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.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.004 (28.2th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 28th percentile — 28.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-19505: held from 0.004 to 0.004.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: -0.000

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-19505?
CVE-2026-19505 is a critical-severity vulnerability, classified under Improper Verification of Cryptographic Signature. CVSS score: 9.8/10. Published 2026-08-19.
How severe is CVE-2026-19505?
Critical severity. CVSS v3 base score is 9.8 out of 10.