CyberSecBulletin
CVE-2023-48306NVD status: Modified

security-advisories: Server-Side Request Forgery

Published Updated By the CyberSecBulletin desk

CVE-2023-48306 is a critical-severity server-side request forgery vulnerability in security-advisories from Nextcloud, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected security-advisories versions: >= 22.0.0, < 22.2.10.16; >= 23.0.0, < 23.0.12.11; >= 24.0.0, < 24.0.12.7, and others listed below. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.8% chance of exploitation within 30 days, higher than 57% of scored CVEs.

Patch this week

Critical severity: a successful attack would have severe impact.

What to do

  1. Update Nextcloud Server to 22.2.10.16 or 23.0.12.11 or 24.0.12.7 or 25.0.11, whichever matches your release line, or a later version.
  2. Read the advisory on github.com for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Nextcloudsecurity-advisories>= 22.0.0, < 22.2.10.16; >= 23.0.0, < 23.0.12.11; >= 24.0.0, < 24.0.12.7; >= 25.0.0, < 25.0.11; >= 26.0.0, < 26.0.6; >= 27.0.0, < 27.1.0Not stated
NextcloudNextcloud Server22.0.0 up to, but not including, 22.2.10.16; 23.0.0 up to, but not including, 23.0.12.11; 24.0.0 up to, but not including, 24.0.12.7; 25.0.0 up to, but not including, 25.0.11; 26.0.0 up to, but not including, 26.0.6; 27.0.0 up to, but not including, 27.1.022.2.10.16, 23.0.12.11, 24.0.12.7, 25.0.11, 26.0.6, 27.1.0

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
HighData or code can be modified at will.
Availability
HighThe component can be taken down completely.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.

Scoring systemScoreSeverityScored by
CVSS 3.15.0MediumCNA (github.com)
CVSS 3.19.8CriticalNVD

Official description

Nextcloud Server provides data storage for Nextcloud, an open source cloud platform. Starting in version 25.0.0 and prior to versions 25.0.11, 26.0.6, and 27.1.0 of Nextcloud Server and starting in version 22.0.0 and prior to versions 22.2.10.16, 23.0.12.11, 24.0.12.7, 25.0.11, 26.0.6, and 27.1.0 of Nextcloud Enterprise Server, the DNS pin middleware was vulnerable to DNS rebinding allowing an attacker to perform SSRF as a final result. Nextcloud Server 25.0.11, 26.0.6, and 27.1.0 and Nextcloud Enterprise Server 22.2.10.16, 23.0.12.11, 24.0.12.7, 25.0.11, 26.0.6, and 27.1.0 contain patches for this issue. No known workarounds are available.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Server-Side Request Forgery

The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.

How developers prevent this class of flaw

  • If there is a known list of applications, IP, hostname, and/or domains to which the product is allowed to communicate, then use allowlists to ensure that outgoing requests are restricted to these known entities. The allowlists could be in the application code or possibly enforced by firewalls or network segmentation.
  • If the product is expected to be able to connect to arbitrary IP addresses or domains, consider using a denylist that includes private network addresses, internal domain names, etc. The denylist could be in the application code or possibly enforced by firewalls or network segmentation.

More Server-Side Request Forgery vulnerabilities (CWE-918)

Timeline

  1. CVE record published.
  2. Record last changed materially (score, affected products, status or references).

References

Patches and release notes

Other references

Other vulnerabilities in security-advisories

All security-advisories vulnerabilities

Recent Server-Side Request Forgery vulnerabilities

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