CVE-2023-46724

SQUID-2023:4 Denial of Service in SSL Certificate validation

HIGH
7.5
CVSS Score
Published: November 1, 2023 at 07:09 PM UTC
Updated: June 17, 2026 at 06:31 AM UTC
2 products affected across 1 vendorSquidCache Squid

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Severity
HIGH7.5
Exploit prediction
EPSS 4%
SSVC
No known exploit

Description

Squid is a caching proxy for the Web. Due to an Improper Validation of Specified Index bug, Squid versions 3.3.0.1 through 5.9 and 6.0 prior to 6.4 compiled using `--with-openssl` are vulnerable to a Denial of Service attack against SSL Certificate validation. This problem allows a remote server to perform Denial of Service against Squid Proxy by initiating a TLS Handshake with a specially crafted SSL Certificate in a server certificate chain. This attack is limited to HTTPS and SSL-Bump. This bug is fixed in Squid version 6.4. In addition, patches addressing this problem for the stable releases can be found in Squid's patch archives. Those who you use a prepackaged version of Squid should refer to the package vendor for availability information on updated packages.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 6.43.3.0.1 ≤ v < 6.4
Affected range stops below 6.4, so it looks safe — our inference, not a vendor statement
v < 6.43.3.0.1 ≤ v < 6.4
Affected range stops below 6.4, so it looks safe — our inference, not a vendor statement

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-125CWE-129CWE-786CWE-823CWE-1285CWE-295

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