How severe is CVE-2026-34839?

CVE-2026-34839 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-34839 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (34th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-34839?

CVE-2026-34839 affects Nicolargo Glances. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-34839?

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

Does CVE-2026-34839 have an EU (EUVD) identifier?

Yes. CVE-2026-34839 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23986.

When was CVE-2026-34839 published?

CVE-2026-34839 was published on 2026-04-21 and last updated on 2026-06-17.

CVE-2026-34839

CVE-2026-34839 is a medium-severity vulnerability in Nicolargo Glances 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-306.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v4: 7.7
EPSS exploit prediction: 0% (34th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-23986
Weakness: CWE-306
Affected product: Nicolargo Glances
Published: 2026-04-21
Last modified: 2026-06-17

Description

Glances is an open-source system cross-platform monitoring tool. Prior to version 4.5.4, the Glances web server exposes a REST API (`/api/4/*`) that is accessible without authentication and allows cross-origin requests from any origin due to a permissive CORS policy (`Access-Control-Allow-Origin: *`). This allows a malicious website to read sensitive system information from a running Glances instance in the victim’s browser, leading to cross-origin data exfiltration. While a previous advisory exists for XML-RPC CORS issues, this report demonstrates that the REST API (`/api/4/*`) is also affected and exposes significantly more sensitive data. Version 4.5.4 patches the issue.

Frequently asked questions

What is CVE-2026-34839?: Glances is an open-source system cross-platform monitoring tool. Prior to version 4.5.4, the Glances web server exposes a REST API (`/api/4/*`) that is accessible without authentication and allows cross-origin requests from any origin due to a permissive CORS policy (`Access-Control-Allow-Origin: *`). This allows a malicious website to read sensitive system information from a running Glances instance in the victim’s browser, leading to cross-origin data exfiltration. While a previous advisory exists for XML-RPC CORS issues, this report demonstrates that the REST API (`/api/4/*`) is also affected and exposes significantly more sensitive data. Version 4.5.4 patches the issue.
How severe is CVE-2026-34839?: CVE-2026-34839 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-34839 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (34th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-34839?: CVE-2026-34839 affects Nicolargo Glances. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-34839?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-34839 have an EU (EUVD) identifier?: Yes. CVE-2026-34839 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-23986.
When was CVE-2026-34839 published?: CVE-2026-34839 was published on 2026-04-21 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:nicolargo:glances:*:*:*:*:*:*:*:*

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