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CVE Record

CVE-2026-32748: Squid has Denial of Service in ICP Response handling

Squid is a caching proxy for the Web. Prior to version 7.5, due to premature release of resource during expected lifetime and heap Use-After-Free bugs, Squid is vulnerable to Denial of Service when handling ICP traffic. This problem allows a remote attacker to perform a reliable and repeatable Denial of Service attack against the Squid service using ICP protocol. This attack is limited to Squid deployments that explicitly enable ICP support (i.e. configure non-zero `icp_port`). This problem _cannot_ be mitigated by denying ICP queries using `icp_access` rules. This bug is fixed in Squid version 7.5.

HighCVSS 8.7Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

Squid proxy servers before 7.5 can be crashed remotely when they handle ICP traffic. The risk is serious because no login or user action is required, but exposure is limited to deployments that explicitly enable ICP with a non-zero icp_port. The supplied sources do not show active exploitation or KEV listing.

Executive priority

Prioritize remediation for Squid proxies with ICP enabled, especially where reachable from untrusted networks. Business impact is service disruption, not data theft according to the supplied CVSS vector. Treat as high priority where proxy availability supports business-critical traffic.

Technical view

The flaw involves premature resource release and heap use-after-free conditions in ICP response handling, mapped to CWE-413, CWE-416, and CWE-826. CVSS 4.0 is 8.7 with network attack vector, low complexity, no privileges, and high availability impact. The vendor states icp_access denial rules do not mitigate it.

Likely exposure

Internet- or partner-reachable Squid instances are exposed only if running a version before 7.5 and configured with icp_port set to a non-zero value. Standard Squid deployments without ICP enabled are not described as affected by the source bundle.

Exploitation context

The advisory says a remote attacker can perform a reliable, repeatable denial-of-service attack against Squid using ICP protocol traffic. The bundle does not cite public exploit activity, CISA KEV inclusion, or exploitation in the wild.

Researcher notes

Focus triage on ICP-enabled Squid before 7.5. The important operational nuance is that access-control denial for ICP queries is explicitly not a mitigation. Evidence in the bundle supports denial of service only; do not infer code execution or confidentiality impact.

Mitigation direction

  • Upgrade Squid to version 7.5 or later where the bug is fixed.
  • Apply relevant vendor packages from Red Hat advisories where applicable.
  • Disable ICP by setting icp_port to zero if ICP is not required.
  • Do not rely on icp_access denial rules as mitigation.
  • Check Squid and OS vendor guidance for deployment-specific remediation.

Validation and detection

  • Inventory Squid versions and identify instances running before 7.5.
  • Review Squid configuration for non-zero icp_port settings.
  • Confirm whether ICP is reachable from untrusted networks.
  • Verify applied vendor errata or package versions after remediation.
  • Monitor Squid availability logs for unexplained crashes or restarts.
Prepared
Confidence
high
Sources
12

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-413: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-416: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cwe · low confidence lookup

CWE-826: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-32748 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
High
CVSS
8.7 (4.0)
Known Exploited
No
Published

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

2CVSS vectors
5Timeline events
3ADP providers
18Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: yesTechnical Impact: partial

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
8.7CVSS 4.0HighCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L——GitHub_M
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 4.0 score

8.7High
CVSS 4.0 vector shape for CVE-2026-32748Attack VectorAttack ComplexityAttack RequirementsPrivileges RequiredUser InteractionVS ConfidentialityVS IntegrityVS AvailabilitySS ConfidentialitySS IntegritySS Availability

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:L

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Attack Requirements
NonePresent
Privileges Required
NoneLowHigh
User Interaction
NonePassiveActive
VS Confidentiality
HighLowNone
VS Integrity
HighLowNone
VS Availability
HighLowNone
SS Confidentiality
HighLowNone
SS Integrity
HighLowNone
SS Availability
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. ADP timelineredhat-SADP

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPSquid: Squid: Denial of Service via crafted ICP traffic
other:Red Hat severity ratingcvssV3_1
  • 2026-03-26T01:01:29.920Z: Reported to Red Hat.
  • 2026-03-26T00:11:01.424Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
squid-cachesquid< 7.5Listed
Weakness

CWE details

CWE-413CWE-416CWE-826

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.

CWE-413 · source CWE mapping

Improper Resource Locking

Improper Resource Locking represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-416 · source CWE mapping

Use After Free

Use After Free represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs
CWE-826 · source CWE mapping

Premature Release of Resource During Expected Lifetime

Premature Release of Resource During Expected Lifetime represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

Open CWE intelligenceSame-CWE CVEs