6.9

CVE-2026-55205: Hermes WebUI < 0.51.468 - Resource Exhaustion via Unauthenticated OAuth Flow Endpoint

Deferred
Published 18-06-2026Last modified 17-09-2026

Vulnerability summary

CVE-2026-55205 is a medium (CVSS 6.9) vulnerability in nesquena hermes-webui. EPSS estimates a 0.52% chance of exploitation in the next 30 days, higher than 43.5% of scored vulnerabilities.

Overall risk
28/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.9/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.52%
0%100%
Low · +0.16 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Timeline

  1. 18-06-2026
    PublishedVulnerability first disclosed.
  2. 17-09-2026
    Last modifiedVulnerability information updated.

Description

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.

CVSS metrics

4 scores · 2 sources · 2 versions

EPSS trend

Probability

0.52%

Chance of exploitation in the next 30 days

Percentile

44%

Versus all other CVEs

30-day change

Increase +0.16 pp

From 0.37% on 22-09-2026

22-09-202622-10-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Nesquena1 product

1 vendor · 1 product

References

5 links