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Mallory
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Squid Denial of Service via crafted ICP traffic

IdentifiersCVE-2026-32748CWE-416· Use After Free

CVE-2026-32748 is a denial-of-service vulnerability in Squid's handling of ICP (Internet Cache Protocol) traffic. In Squid versions prior to 7.5, premature release of a resource during its expected lifetime leads to heap use-after-free conditions while processing ICP requests. A remote attacker can send crafted ICP traffic to trigger the flaw and reliably, repeatedly crash or otherwise disrupt the Squid service. The issue is limited to deployments that explicitly enable ICP support via a non-zero icp_port. Advisory material notes that affected release lines include Squid 3.x through 7.4.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows a remote, unauthenticated attacker to cause a reliable and repeatable denial of service against the Squid proxy service over the network using ICP traffic. The documented impact is loss of availability of the Squid service. Although an oss-security discussion noted that heap use-after-free bugs can sometimes have broader consequences, the provided advisory content specifically characterizes this issue as denial of service.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, disable ICP support. Squid's advisory recommends not enabling ICP and explicitly setting icp_port 0 as a workaround. icp_access rules are not an effective mitigation for this issue; denying ICP queries with icp_access does not prevent exploitation. Administrators can verify whether ICP is enabled by checking for a non-zero ICP-related port in the active configuration.

Remediation

Patch, then assume compromise.

Upgrade Squid to version 7.5 or later, which contains the fix for this vulnerability. For environments using vendor-packaged builds, obtain and apply the vendor-provided update that incorporates the upstream fix. The provided references also identify a fixing change in Squid commit 703e07d25ca6fa11f52d20bf0bb879e22ab7481b for the Squid 7 branch.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
Squid-CacheSquidapplication

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What this page doesn’t show

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Exposure mapping

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Threat actor evidence

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Associated malware

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Detection signatures

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Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity10

Community discussion across Reddit, Mastodon, and other social sources.