How severe is CVE-2026-55198?

CVE-2026-55198 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-55198 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-55198?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-55198 have an EU (EUVD) identifier?

Yes. CVE-2026-55198 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-37779.

When was CVE-2026-55198 published?

CVE-2026-55198 was published on 2026-06-17.

CVE-2026-55198

CVE-2026-55198 is a medium-severity vulnerability with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-639.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v4: 7.1
EPSS exploit prediction: 0% (19th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-37779
Weakness: CWE-639
Published: 2026-06-17
Last modified: 2026-06-17

Description

Hermes WebUI before 0.51.443 contains an authorization bypass vulnerability in the session export endpoint that allows authenticated users to access sessions from other profiles. The _handle_session_export handler in api/routes.py fails to verify active-profile ownership before serializing session data, enabling attackers to exfiltrate foreign session transcripts by guessing or knowing session identifiers.

Frequently asked questions

What is CVE-2026-55198?: Hermes WebUI before 0.51.443 contains an authorization bypass vulnerability in the session export endpoint that allows authenticated users to access sessions from other profiles. The _handle_session_export handler in api/routes.py fails to verify active-profile ownership before serializing session data, enabling attackers to exfiltrate foreign session transcripts by guessing or knowing session identifiers.
How severe is CVE-2026-55198?: CVE-2026-55198 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-55198 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-55198?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-55198 have an EU (EUVD) identifier?: Yes. CVE-2026-55198 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-37779.
When was CVE-2026-55198 published?: CVE-2026-55198 was published on 2026-06-17.

References

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