CVE-2026-49955 Hermes WebUI < 0.51.270 Resource Exhaustion via passkey/options
Unauthenticated attackers can cause denial of service in Hermes WebUI by exhausting resources via repeated passkey option requests.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-49955?
CVE-2026-49955 is a medium-severity denial of service vulnerability in nesquena hermes-webui, published on 9 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-770
Which versions are affected by CVE-2026-49955?
How do I fix CVE-2026-49955?
No fix has been published for CVE-2026-49955 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-49955 being exploited?
There is no known exploitation of CVE-2026-49955 in the wild and no public exploit code.
Sources
Also known as GHSA-wwx5-jq7h-rp7v.