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VulnerabilityPublished

CVE-2026-45286: nextcloud security-advisories · Information Exposure

Affects nextcloud security-advisoriesSource CVE Database V5

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Not known to be exploited · CVSS 4.3 Medium : upgrade to 6.2.3 or 5.5.17 when convenient.

Data as of 29 Oct 2026, 19:04 UTC

CVSS 3.1 base score
4.3Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 20% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 6.2.3, 5.5.17
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 1 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

What to do

Upgrade security-advisories and nextcloud/calendar to 6.2.3 or 5.5.17.

Affected software

ProductAffectedFixed in
nextcloudsecurity-advisoriesAffected
  • >=6.2.0 <6.2.3
Fixed in
  • 6.2.3
nextcloudsecurity-advisoriesAffected
  • >=5.5.13 <5.5.17
Fixed in
  • 5.5.17
GitHubnextcloud/calendarpkg:github/nextcloud/calendarOther threatsAffected
  • >=5.5.13 <5.5.17
  • >=6.2.0 <6.2.3
Fixed in
  • 5.5.17
  • 6.2.3

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade Nextcloud to version 5.5.17 or later, or 6.2.3 or later, where this vulnerability has been patched. Since this is not a cloud service, administrators must apply these updates manually. Patch status is confirmed by the vendor advisory stating the fix is included in these versions.

Description

Nextcloud versions 5.5.13 to before 5.5.17 and 6.2.0 to before 6.2.3 contain a vulnerability where an authenticated user can enumerate other users on the same instance via the Calendar app's attendee suggestion endpoint. This endpoint did not enforce sharing restrictions that were applied elsewhere, leading to exposure of user information.

References

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