A logic error in Nextcloud Server 19.0.0 caused a privilege escalation allowing malicious users to reshare with higher permissions than the…

published 2020-10-05 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-29096

cvss: 6.5; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.5%; EPSS 1.5% chance of exploitation in 30 days, percentile 73%
public exploits: 0; none known

A logic error in Nextcloud Server 19.0.0 caused a privilege escalation allowing malicious users to reshare with higher permissions than they got assigned themselves.

Exploit prediction

1.47% chance of exploitation in the next 30 days, higher than 73% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

hackerone.com https://hackerone.com/reports/889243 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
NVD	2.0	3.5	AV:N/AC:M/Au:S/C:N/I:P/A:N

Affected products

n/a Nextcloud Server

Classification

Weakness

CWE-269 Improper Privilege Management

References

hackerone.com /reports/889243
exploit, third-party-advisory
lists.fedoraproject.org /archives/list/package-announce%40lists.fedoraproject.org/message/KC6HLX5SG4PZO6Y54D2LFJ4ATG76BKOP/
vendor-advisory
lists.fedoraproject.org /archives/list/package-announce%40lists.fedoraproject.org/message/T7FX3O6SJE2S52I2HAA4DSTUIISP5BNA/
vendor-advisory
nextcloud.com /security/advisory/?id=NC-SA-2020-029
vendor-advisory

Sources

CVE List CVE-2020-8223
NVD CVE-2020-8223

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary