CVE-2026-49955 Details
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.
A resource exhaustion vulnerability has been identified in Hermes WebUI versions prior to 0.51.270. This vulnerability allows unauthenticated remote attackers to degrade service availability by repeatedly sending POST requests to the passkey options endpoint without completing the required assertion. The excessive requests cause unbounded growth of the challenge store file, leading to increased CPU and disk I/O as the application repeatedly rewrites the JSON file. This vulnerability can fill up the challenge store, potentially causing a denial of service by blocking legitimate authentication requests until the stored challenges expire.
Users can update to Hermes WebUI version 0.51.270 or later, where this vulnerability has been fixed.
Metrics
CVSS 4.0 Severity and Vector Strings:
VolerionCVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
Volerion
Assessed Jun 9, 2026CISA-ADP
Assessed Jun 9, 2026References to Advisories, Solutions, and Tools
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| URL | Source(s) | Tag(s) |
|---|---|---|
| https://github.com/nesquena/hermes-webui/commit/58528a4d88b0fa4f7b822e31d6051c669769bd3b | [email protected] | Source CodeVendor |
| https://github.com/nesquena/hermes-webui/pull/3624 | [email protected] | Issue TrackingVendor |
| https://github.com/nesquena/hermes-webui/pull/3674 | [email protected] | Issue TrackingRelease NotesVendor |
| https://github.com/nesquena/hermes-webui/releases/tag/v0.51.270 | [email protected] | Release NotesVendor |
| https://www.vulncheck.com/advisories/hermes-webui-resource-exhaustion-via-passkey-options | [email protected] | AdvisoryBundleRemedy |
Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| CWE-770 | Allocation of Resources Without Limits or Throttling | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| Hermes WebUI | < 0.51.270 (semver) |
CPE
Remediation
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Change History
5 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 23, 2026 | CVE Translated | [email protected] |
| Jul 14, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Jun 9, 2026 | New CVE Received | [email protected] |