CVE-2023-5824
Public on
Last Modified:
Description
A flaw was found in Squid. The limits applied for validation of HTTP response headers are applied before caching. However, Squid may grow a cached HTTP response header beyond the configured maximum size, causing a stall or crash of the worker process when a large header is retrieved from the disk cache, resulting in a denial of service.
Statement
This vulnerability only affects configurations with the cache_dir directive enabled. If this directive is not enabled, the Squid server is not vulnerable and no further mitigation is needed. For more information about the mitigation, see the mitigation section below.
The cache_dir directive is disabled by default in Squid shipped in Red Hat Enterprise Linux 6, 7, 8 and 9. Therefore, these Red Hat Enterprise Linux versions are not vulnerable with the default configuration.
Red Hat is not planning to address this issue in Red Hat Enterprise Linux 6 and 7 due to the changes required and the magnitude of the differences between Squid 3 and 4 code bases, backporting the changes to the Squid 3 code base has not been feasible.
We recommend that customers using Squid as a caching proxy on Red Hat Enterprise Linux 6 and 7 to upgrade to Red Hat Enterprise Linux 8 and 9 to use Squid version 4 or version 5, respectively. Alternatively, see the mitigation section below for a way to workaround this vulnerability.
Mitigation
Disabling the disk caching mechanism will mitigate this vulnerability. To achieve this, remove all the 'cache_dir' directives from the Squid configuration, typically in the /etc/squid/squid.conf file.
Additional information
- Bugzilla 2245914: squid: DoS against HTTP and HTTPS
- CWE-755: Improper Handling of Exceptional Conditions
- FAQ: Frequently asked questions about CVE-2023-5824
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 | 7.5 | 7.5 |
Attack Vector | Network | Network |
Attack Complexity | Low | Low |
Privileges Required | None | None |
User Interaction | None | None |
Scope | Unchanged | 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:N/S:U/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
Understanding the Weakness (CWE)
Other
Technical Impact: Other
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?
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