Vulnerability record/PUBLISHED/Published Jun 9, 2026 16:05:33 UTC

CVE-2026-49955

Hermes WebUI before version 0.51.270 contains a resource exhaustion vulnerability that allows unauthenticated remote attackers to degrade service availability by repeatedly calling the passkey options endpoint without completing assertion. Attackers can send unlimited POST requests to the authentication endpoint, causing unbounded growth of the challenge store file and excessive CPU and disk I/O through repeated JSON file rewrites.

Base score6.9/ 10

SeverityMediumCVSS 4.0

Exploitability / impact

CVSS metric breakdown

Vector-derived attributes

Base severityMedium

Attack vectorNetworkAV

Attack complexityLowAC

Attack requirementsNoneAT

Privileges requiredNonePR

User interactionNoneUI

Vulnerable system confidentialityNoneVC

Vulnerable system integrityNoneVI

Vulnerable system availabilityLowVA

Subsequent system confidentialityNoneSC

Subsequent system integrityNoneSI

Subsequent system availabilityNoneSA

CVSS vector stringCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

CVSS communicates standardized severity and impact characteristics. It does not establish whether a system is exploitable in your specific environment.

Record context

CVE Numbering AuthorityVulnCheck

Last updatedNov 8, 2026 14:04:57 UTC

PublishedJun 9, 2026 16:05:33 UTC

ReservedJun 2, 2026 16:30:15 UTC

Credits

Chia Min Jun Lennon