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Fencer Intel
medium 6.5

CVE-2020-8138 json

A missing check for IPv4 nested inside IPv6 in Nextcloud server < 17.0.1, < 16.0.7, and < 15.0.14 allowed a Server-Side Request Forgery (SS…

published 6y ago modified 4mo ago also EUVD-2020-29035

cvss
6.5
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 missing check for IPv4 nested inside IPv6 in Nextcloud server < 17.0.1, < 16.0.7, and < 15.0.14 allowed a Server-Side Request Forgery (SSRF) vulnerability when subscribing to a malicious calendar URL.

Patch / fix

  • nextcloud nextcloud_server 15.0.14, 16.0.7, 17.0.2

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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-2020-8138 updated cvss 6.5

nextcloud: a Server-Side Request Forgery vulnerability when subscribing to a malicious calendar URL

  • 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, 2026-11-09).

Exploits and checks

  • hackerone.com https://hackerone.com/reports/736867 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:L/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 4.0 AV:N/AC:L/Au:S/C:P/I:N/A:N

Affected products

  • n/a Nextcloud Server

Classification

Weakness
  • CWE-918 Server-Side Request Forgery

References

Sources

Fencer Intel 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.