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Fencer Vulns
medium 5.4

CVE-2020-8189 json

A cross-site scripting error in Nextcloud Desktop client 2.6.4 allowed to present any html (including local links) when responding with inv…

published 2020-08-21 6 y ago modified 2026-06-17 4 mo ago also EUVD-2020-29067

cvss
5.4
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
1.4%
EPSS 1.4% chance of exploitation in 30 days, percentile 72%
public exploits
0
none known

Summary

A cross-site scripting error in Nextcloud Desktop client 2.6.4 allowed to present any html (including local links) when responding with invalid data on the login attempt.

Patch / fix

  • nextcloud desktop 2.6.5
  • nextcloud-desktop Debian 14, Debian 13, Debian 12 3.0.1-1

debian advisories DEBIAN-CVE-2020-8189

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-8189 updated cvss 4.7

nextcloud: XSS on the login attempt

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

1.40% chance of exploitation in the next 30 days, higher than 72% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • hackerone.com https://hackerone.com/reports/685552 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
NVD 3.1 5.4 CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
NVD 2.0 3.5 AV:N/AC:M/Au:S/C:N/I:P/A:N

Affected products

  • n/a Desktop Client

Classification

Weakness
  • CWE-79 Improper Neutralization of Input During Web Page Generation

References

Sources

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.