Security Resilience

CVE-2023-49285

Memory Safety in Squid-Cache Squid ≤ 6.4

High EPSSMemory Safety
Published
04 December 2023
Modified
21 November 2024
Patch / advisory
CVSS Score v3.1 8.6
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
EPSS Score 0.88 99.8th percentile
Risk Priority 88 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2023-49285 is a high-severity Buffer Over-read (CWE-126) vulnerability in Squid-Cache Squid. Its CVSS base score is 8.6 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Data Obfuscation (T1001); ranked in the top 0.2% of CVEs by exploit likelihood; it is not currently listed in the CISA KEV catalog.

Deeper analysis AI-assisted summary

Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.

Squid, a widely used caching proxy supporting HTTP, HTTPS, FTP and related protocols, contains a buffer overread vulnerability in its HTTP message processing code. The flaw, tracked as CVE-2023-49285 and assigned CWE-126 and CWE-125, allows an attacker to trigger a denial of service by supplying specially crafted input that causes Squid to read beyond allocated buffer boundaries. The issue affects multiple maintained release lines prior to the 6.5 release and carries a CVSS 3.1 base score of 8.6 reflecting network attack vector, low complexity, and high availability impact with no required privileges or user interaction.

An unauthenticated remote attacker can send malicious HTTP messages directly to an exposed Squid instance, causing the proxy to crash or become unresponsive. Because the vulnerability resides in core message parsing, the attack can be mounted against any deployment that accepts untrusted client or server traffic, including forward and reverse proxy configurations.

Official advisories and patches published by the Squid project state that the bug is resolved in version 6.5 and provide back-ported fixes for the 5.x series via the referenced SQUID-2023_7 patches and corresponding Git commits. No workarounds are documented, and administrators are advised to upgrade immediately. The associated EPSS score has remained low and stable near 0.096, indicating limited observed exploitation interest to date.

EU & UK References

Vulnerability Data

Squid is a caching proxy for the Web supporting HTTP, HTTPS, FTP, and more. Due to a Buffer Overread bug Squid is vulnerable to a Denial of Service attack against Squid HTTP Message processing. This bug is fixed by Squid…

more

version 6.5. Users are advised to upgrade. There are no known workarounds for this vulnerability.

CWE(s)

Related Threats

MITRE ATT&CK Enterprise Techniques

T1001 Data Obfuscation Command And Control
Adversaries may obfuscate command and control traffic to make it more difficult to detect.
T1001.002 Steganography Command And Control
Adversaries may use steganographic techniques to hide command and control traffic to make detection efforts more difficult.
T1001.003 Protocol or Service Impersonation Command And Control
Adversaries may impersonate legitimate protocols or web service traffic to disguise command and control activity and thwart analysis efforts.
T1003 OS Credential Dumping Credential Access
Adversaries may attempt to dump credentials to obtain account login and credential material, normally in the form of a hash or a clear text password.
T1003.002 Security Account Manager Credential Access
Adversaries may attempt to extract credential material from the Security Account Manager (SAM) database either through in-memory techniques or through the Windows Registry where the SAM database is stored.
T1003.003 NTDS Credential Access
Adversaries may attempt to access or create a copy of the Active Directory domain database in order to steal credential information, as well as obtain other information about domain members such as devices, users, and access rights.
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-47729Same product: Squid-Cache Squid
CVE-2026-33515Same product: Squid-Cache Squid
CVE-2023-46724Same product: Squid-Cache Squid
CVE-2024-9843Shared CWE-125, CWE-126
CVE-2024-45559Shared CWE-125, CWE-126
CVE-2024-33047Shared CWE-125, CWE-126
CVE-2024-21459Shared CWE-125, CWE-126
CVE-2023-33115Shared CWE-125, CWE-126
CVE-2024-33050Shared CWE-125, CWE-126
CVE-2023-43527Shared CWE-125, CWE-126

Affected Assets

squid-cache
squid
≤ 6.4

Mitigating Controls

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

ID.RA-01 partial match
blocks

Vulnerability identification processes can discover buffer over-read flaws via scanning or review.

PR.PS-02 partial match
blocks

Patching or replacing vulnerable software removes known instances of buffer over-read bugs.

PR.PS-06 partial match
blocks

Secure development practices directly prevent introduction of buffer over-read weaknesses.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

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References