CVE-2021-28651
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Description
An input validation flaw was found in Squid. This issue could allow a malicious server in collaboration with a trusted client to consume arbitrarily large amounts of memory on the server running Squid. The highest threat from this vulnerability is to system availability.
Statement
This issue has been rated as having a security impact of Moderate. At this stage in their life, Red Hat Enterprise Linux 6 and 7 only accept Important and Critical Security Advisories (RHSAs) and this flaw does not meet these criteria. For additional information, refer to the Red Hat Enterprise Linux Life Cycle: https://access.redhat.com/support/policy/updates/errata.
Red Hat Satellite does not ship the Squid package, however, does consume it from RHEL 7 repository. Product is not affected by this flaw as squid.conf configuration disables all the http_access fragments except the localhost.
Mitigation
If possible, disable URN processing by adding the following lines in `squid.conf`:
acl URN proto URN
http_access deny URN
Additional information
- Bugzilla 1962243: squid: denial of service in URN processing
- CWE-401->CWE-400: Missing Release of Memory after Effective Lifetime leads to Uncontrolled Resource Consumption
- FAQ: Frequently asked questions about CVE-2021-28651
Common Vulnerability Scoring System (CVSS) Score Details
Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
| Red Hat | NVD | |
|---|---|---|
CVSS v3 Base Score | 7.4 | 7.5 |
Attack Vector | Network | Network |
Attack Complexity | Low | Low |
Privileges Required | None | None |
User Interaction | Required | None |
Scope | Changed | Unchanged |
Confidentiality Impact | None | None |
Integrity Impact | None | None |
Availability Impact | High | High |
CVSS v3 Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:N/I:N/A:H
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Acknowledgements
Upstream acknowledges Joshua Rogers (Opera Software) as the original reporter.
Frequently Asked Questions
Why is Red Hat's CVSS v3 score or Impact different from other vendors?
My product is listed as "Under investigation" or "Affected", when will Red Hat release a fix for this vulnerability?
What can I do if my product is listed as "Will not fix"?
What can I do if my product is listed as "Fix deferred"?
What is a mitigation?
I have a Red Hat product but it is not in the above list, is it affected?
Why is my security scanner reporting my product as vulnerable to this vulnerability even though my product version is fixed or not affected?
My product is listed as "Out of Support Scope". What does this mean?
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