How severe is CVE-2026-19505?

CVE-2026-19505 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2026-19505 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (28th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-19505?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2026-19505 published?

CVE-2026-19505 was published on 2026-08-19 and last updated on 2026-09-03.

CVE-2026-19505

CVE-2026-19505 is a critical-severity vulnerability with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-347.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
EPSS exploit prediction: 0% (28th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-347
Published: 2026-08-19
Last modified: 2026-09-03

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.

Frequently asked questions

What is 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.
How severe is CVE-2026-19505?: CVE-2026-19505 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2026-19505 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (28th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-19505?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2026-19505 published?: CVE-2026-19505 was published on 2026-08-19 and last updated on 2026-09-03.

References

Other CWE-347 (Improper Verification of Cryptographic Signature) vulnerabilities

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