CVE-2023-5824

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.

Squid is a high-performance proxy caching server. It handles all requests in a single, non-blocking, I/O-driven process and keeps meta data and implements negative caching of failed requests.

Security Fix(es):

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.(CVE-2023-5824)

Squid is a high-performance proxy caching server. It handles all requests in a single, non-blocking, I/O-driven process and keeps meta data and implements negative caching of failed requests.

Security Fix(es):

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.(CVE-2023-5824)

Squid is a high-performance proxy caching server. It handles all requests in a single, non-blocking, I/O-driven process and keeps meta data and implements negative caching of failed requests.

Security Fix(es):

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.(CVE-2023-5824)

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.

Squid is a high-performance proxy caching server for web clients, supporting FTP, Gopher, and HTTP data objects.

Security Fix(es):

• squid: DoS against HTTP and HTTPS (CVE-2023-5824)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Squid is a high-performance proxy caching server for web clients, supporting FTP, Gopher, and HTTP data objects.

Security Fix(es):

• squid: DoS against HTTP and HTTPS (CVE-2023-5824)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

• CVE-2023-5824: Fix improper handling of structural elements to prevent DoS attacks against HTTP and HTTPS clients

• CVE-2023-5824: Remove serialized HTTP headers from storeClientCopy()

• CVE-2023-5824: do not send serialized HTTP response header bytes in storeClientCopy() answers. Ignore serialized header size when calling storeClientCopy().

• SECURITY UPDATE: excessive cached HTTP response header size causing worker process stall or crash
  • debian/patches/CVE-2023-5824.patch: Refactor serialized HTTP response header handling to prevent cache flow
  • CVE-2023-5824
• SECURITY UPDATE: Use-After-Free in the HTTP Collapsed Forwarding Feature
  • debian/patches/CVE-2023-5824.patch: Removed Use-After-Free during refactor serialized HTTP response header
  • CVE-2023-49288

Affected versions of squid are subject to a Use-After-Free bug which can lead to a Denial of Service attack via collapsed forwarding. All versions of Squid from 3.5 up to and including 5.9 configured with "collapsed_forwarding on" are vulnerable. Configurations with "collapsed_forwarding off" or without a "collapsed_forwarding" directive are not vulnerable. (CVE-2023-49288) Squid is vulnerable to Denial of Service attack against HTTP and HTTPS clients due to an Improper Handling of Structural Elements bug. (CVE-2023-5824)

These are all security issues fixed in the squid-6.4-1.1 package on the GA media of openSUSE Tumbleweed.

Squid is a high-performance proxy caching server for web clients, supporting FTP, Gopher, and HTTP data objects.

Security Fix(es):

• squid: DoS against HTTP and HTTPS (CVE-2023-5824)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

This update for squid fixes the following issues:

• CVE-2023-5824: Multiple issues in HTTP response caching (bsc#1216496).
• CVE-2023-49288: Use-After-Free in the HTTP Collapsed Forwarding Feature (bsc#1217825).
• CVE-2025-62168: failure to redact HTTP authentication credentials in error handling leads to the disclosure of credentials a trusted client uses to authenticate (bsc#1252281).
• CVE-2026-32748: denial of service in ICP Request handling (bsc#1260453).
• CVE-2026-33515: out of bounds read in ICP message handling (bsc#1260454).
• CVE-2026-33526: denial of service in ICP Request handling (bsc#1260452).
• CVE-2026-47729: out-of-bounds read attack against the ftp gateway due to a improper validation of syntactic correctness of input (bsc#1268272).
• CVE-2026-50012: Improper Input Validation bug (bsc#1268320).

Joshua Rogers discovered that Squid incorrectly handled collapsed forwarding. A remote attacker could possibly use this issue to cause Squid to crash, resulting in a denial of service. This issue only affected Ubuntu 20.04 LTS and Ubuntu 22.04 LTS. (CVE-2023-49288)

Joshua Rogers discovered that Squid incorrectly handled certain structural elements. A remote attacker could possibly use this issue to cause Squid to crash, resulting in a denial of service. (CVE-2023-5824)

Joshua Rogers discovered that Squid incorrectly handled Cache Manager error responses. A remote trusted client can possibly use this issue to cause Squid to crash, resulting in a denial of service. (CVE-2024-23638)

Joshua Rogers discovered that Squid incorrectly handled the HTTP Chunked decoder. A remote attacker could possibly use this issue to cause Squid to stop responding, resulting in a denial of service. (CVE-2024-25111)

Joshua Rogers discovered that Squid incorrectly handled HTTP header parsing. A remote trusted client can possibly use this issue to cause Squid to crash, resulting in a denial of service. (CVE-2024-25617)

USN-6728-1 fixed vulnerabilities in Squid. The fix for CVE-2023-5824 caused Squid to crash in certain environments on Ubuntu 20.04 LTS and was disabled in USN-6728-2. The problematic fix for CVE-2023-5824 has now been corrected and reinstated in this update.

We apologize for the inconvenience.

Original advisory details:

Joshua Rogers discovered that Squid incorrectly handled collapsed forwarding. A remote attacker could possibly use this issue to cause Squid to crash, resulting in a denial of service. This issue only affected Ubuntu 20.04 LTS and Ubuntu 22.04 LTS. (CVE-2023-49288)

Joshua Rogers discovered that Squid incorrectly handled certain structural elements. A remote attacker could possibly use this issue to cause Squid to crash, resulting in a denial of service. (CVE-2023-5824)

Joshua Rogers discovered that Squid incorrectly handled Cache Manager error responses. A remote trusted client can possibly use this issue to cause Squid to crash, resulting in a denial of service. (CVE-2024-23638)

Joshua Rogers discovered that Squid incorrectly handled the HTTP Chunked decoder. A remote attacker could possibly use this issue to cause Squid to stop responding, resulting in a denial of service. (CVE-2024-25111)

Joshua Rogers discovered that Squid incorrectly handled HTTP header parsing. A remote trusted client can possibly use this issue to cause Squid to crash, resulting in a denial of service. (CVE-2024-25617)