How severe is CVE-2026-45691?

CVE-2026-45691 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity high, and availability none.

Is CVE-2026-45691 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-45691?

CVE-2026-45691 primarily affects Nextcloud Nextcloud Server. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-45691?

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

Does CVE-2026-45691 have an EU (EUVD) identifier?

Yes. CVE-2026-45691 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-33718.

When was CVE-2026-45691 published?

CVE-2026-45691 was published on 2026-06-01 and last updated on 2026-06-17.

CVE-2026-45691

CVE-2026-45691 is a medium-severity vulnerability in Nextcloud Nextcloud Server with a CVSS 3.x base score of 5.9. 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-287.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
EPSS exploit prediction: 0% (21st percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-33718
Weakness: CWE-287
Affected product: Nextcloud Nextcloud Server
Published: 2026-06-01
Last modified: 2026-06-17

Description

Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.9, and 33.0.0 to before 33.0.3, a pre-2FA session cookie (created after successful password authentication but before TOTP completion) could be reused as a Bearer token to authenticate against DAV endpoints, granting read/write access and bypassing mandatory two-factor authentication. It is recommended that the Nextcloud Server is upgraded to 33.0.3 or 32.0.9. It is recommended that the Nextcloud Enterprise Server is upgraded to 33.0.3, 32.0.9, 31.0.14.5, 30.0.17.9 or 29.0.16.16

Frequently asked questions

What is CVE-2026-45691?: Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.9, and 33.0.0 to before 33.0.3, a pre-2FA session cookie (created after successful password authentication but before TOTP completion) could be reused as a Bearer token to authenticate against DAV endpoints, granting read/write access and bypassing mandatory two-factor authentication. It is recommended that the Nextcloud Server is upgraded to 33.0.3 or 32.0.9. It is recommended that the Nextcloud Enterprise Server is upgraded to 33.0.3, 32.0.9, 31.0.14.5, 30.0.17.9 or 29.0.16.16
How severe is CVE-2026-45691?: CVE-2026-45691 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is low, integrity high, and availability none.
Is CVE-2026-45691 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (21st percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-45691?: CVE-2026-45691 primarily affects Nextcloud Nextcloud Server. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-45691?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-45691 have an EU (EUVD) identifier?: Yes. CVE-2026-45691 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-33718.
When was CVE-2026-45691 published?: CVE-2026-45691 was published on 2026-06-01 and last updated on 2026-06-17.

References

Affected products (2)

cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:-:*:*:*
cpe:2.3:a:nextcloud:nextcloud_server:*:*:*:*:enterprise:*:*:*

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