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CVE-2026-61642

Status: Awaiting AnalysisHigh (7.7)—
Severity7.7High · CVSS 3.1
Exploitation probability4.68 %higher than 92% of CVEs
Active exploitationNonot in the CISA catalog
Public exploitNot knownno public code found

Squid is a caching proxy for the Web. From 3.3.0.1 to before 7.6, due to an improper enforcement of behavioral workflow bug, Squid is vulnerable to a Request Smuggling attack against HTTP/1.1 Transfer-Encoding. HTTP header parsing (`src/HttpHeader.cc`) accepted the bare` Transfer-Encoding:` identity form, which the HTTP specification prohibits because any transfer coding must be wrapped within chunked encoding. This problem allows a trusted client to perform an HTTP Request Smuggling attack when HTTP/1.1 is used, bypassing security mechanisms that may be in place between attacker and Squid.

Read full descriptionShow less

When there is an HTTP cache operating prior to the affected Squid, this Request Smuggling attack also allows the attacker to poison that web cache and store arbitrary malicious content at any URL for delivery to other clients' future requests. This issue is fixed in version 7.6.

CVSS

Base score
7.7
Version
3.1
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N

Exploitation probability (EPSS)

Probability of exploitation in the next 30 days
4.68 %
Percentile among all scored CVEs
92
Score date
10/20/2026

EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).

ATT&CK techniques

How this vulnerability is exploited and what the attacker gains, in MITRE ATT&CK terms.

El vector es AV:N con PR:L y UI:N, y el texto describe request smuggling que evita controles y envenena la caché con contenido malicioso, lo que encaja con manipulación de datos almacenados.

Inferred by our analysis agent from the official description, CVSS vector and CWE, and checked by a supervisor. May contain errors.

ATT&CK mitigations that cover these techniques

Vulnerability ScanningThreat Intelligence ProgramRestrict File and Directory PermissionsPrivileged Account ManagementRemote Data StorageNetwork Segmentation

Affected technologies (1)

⚠ AI-inferred from the description — NVD hasn't analyzed this CVE yet, these aren't verified CPEs.

Squid-cache — SquidAI

CWEs

References

Show 6 references

Raw JSON (NVD)

Show
{
  "id": "CVE-2026-61642",
  "cveTags": [],
  "metrics": {
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-61642",
          "role": "CISA Coordinator",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "version": "2.0.3",
          "timestamp": "2026-10-13T17:54:12.882325Z"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "security-advisories@github.com",
        "cvssData": {
          "scope": "CHANGED",
          "version": "3.1",
          "baseScore": 7.7,
          "attackVector": "NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "NONE",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 4,
        "exploitabilityScore": 3.1
      }
    ]
  },
  "affected": [
    {
      "source": "security-advisories@github.com",
      "affectedData": [
        {
          "vendor": "squid-cache",
          "product": "squid",
          "versions": [
            {
              "status": "affected",
              "version": ">= 3.3.0.1, < 7.6"
            }
          ]
        }
      ]
    }
  ],
  "published": "2026-10-13T17:17:42.670",
  "references": [
    {
      "url": "https://github.com/squid-cache/squid/commit/d06f48de8b8cc9a378cb91ecfe8e89b6e81696d2",
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/squid-cache/squid/commit/d808a7c825a70275113790471135c9c4d547ee51",
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/squid-cache/squid/pull/2427",
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/squid-cache/squid/pull/2431",
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/squid-cache/squid/releases/tag/SQUID_7_6",
      "source": "security-advisories@github.com"
    },
    {
      "url": "https://github.com/squid-cache/squid/security/advisories/GHSA-537g-4gfh-w7m6",
      "source": "security-advisories@github.com"
    }
  ],
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "type": "Secondary",
      "source": "security-advisories@github.com",
      "description": [
        {
          "lang": "en",
          "value": "CWE-444"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "Squid is a caching proxy for the Web. From 3.3.0.1 to before 7.6, due to an improper enforcement of behavioral workflow bug, Squid is vulnerable to a Request Smuggling attack against HTTP/1.1 Transfer-Encoding. HTTP header parsing (`src/HttpHeader.cc`) accepted the bare` Transfer-Encoding:` identity form, which the HTTP specification prohibits because any transfer coding must be wrapped within chunked encoding. This problem allows a trusted client to perform an HTTP Request Smuggling attack when HTTP/1.1 is used, bypassing security mechanisms that may be in place between attacker and Squid. When there is an HTTP cache operating prior to the affected Squid, this Request Smuggling attack also allows the attacker to poison that web cache and store arbitrary malicious content at any URL for delivery to other clients' future requests. This issue is fixed in version 7.6."
    }
  ],
  "lastModified": "2026-10-16T16:00:33.533",
  "sourceIdentifier": "security-advisories@github.com"
}