5.3Medium
CVE-2026-55205
Hermes WebUI before 0.51.468 contains a resource exhaustion vulnerability in the unauthenticated POST /api/onboarding/oauth/start endpoint that allows unbounded accumulation of in-memory flow state and daemon threads. Attackers can send repeated or concurrent requests to exhaust server memory and thread resources, potentially triggering repeated outbound device-code requests to upstream OAuth providers.
What this means for your business
- An attacker can use it remotely, over a network, without a login, and without anyone at your company clicking anything.
- FIRST's prediction model gives it a 0.4% chance of attack attempts being seen in the next 30 days, ranking above 30% of all known flaws.
What to do
- 1Ask your IT team or provider whether any of your systems use the affected product.
- 2If you do, follow the vendor's guidance. No patch reference has been published yet.
Not sure if your company is exposed?
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Scoring
- CVSS
- 5.3 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L- CVSS v4
- 6.9
- Weakness
- CWE-770
- Assigned by
- disclosure@vulncheck.com
Dates
- Published
- 2026-06-18
- Last modified
- 2026-09-17
- Sources
- NVD
References
- https://github.com/nesquena/hermes-webui/commit/ce272d9cd5f8e5a4521278f56eb5388010901646
- https://github.com/nesquena/hermes-webui/pull/3970
- https://github.com/nesquena/hermes-webui/pull/4338
- https://github.com/nesquena/hermes-webui/releases/tag/v0.51.468
- https://www.vulncheck.com/advisories/hermes-webui-resource-exhaustion-via-unauthenticated-oauth-flow-endpoint
- https://github.com/nesquena/hermes-webui/pull/3970