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CVE-2021-28662

Status: ModifiedMedium (6.5)—

An issue was discovered in Squid 4.x before 4.15 and 5.x before 5.0.6. If a remote server sends a certain response header over HTTP or HTTPS, there is a denial of service. This header can plausibly occur in benign network traffic.

CVSS

Exploitation probability (EPSS)

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).

Affected technologies (3)

Debian — Debian LinuxFedoraproject — FedoraSquid-cache — Squid

CWEs

References

Raw JSON (NVD)

Show
{
  "id": "CVE-2021-28662",
  "cveTags": [],
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          "vectorString": "AV:N/AC:M/Au:N/C:N/I:N/A:P",
          "authentication": "NONE",
          "integrityImpact": "NONE",
          "accessComplexity": "MEDIUM",
          "availabilityImpact": "PARTIAL",
          "confidentialityImpact": "NONE"
        },
        "acInsufInfo": false,
        "impactScore": 2.9,
        "baseSeverity": "MEDIUM",
        "obtainAllPrivilege": false,
        "exploitabilityScore": 8.6,
        "obtainUserPrivilege": false,
        "obtainOtherPrivilege": false,
        "userInteractionRequired": true
      }
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    "cvssMetricV31": [
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          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "REQUIRED",
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      "lang": "en",
      "value": "An issue was discovered in Squid 4.x before 4.15 and 5.x before 5.0.6. If a remote server sends a certain response header over HTTP or HTTPS, there is a denial of service. This header can plausibly occur in benign network traffic."
    },
    {
      "lang": "es",
      "value": "Se detectó un problema en Squid versiones 4.x anteriores a 4.15 y versiones 5.x anteriores a 5.0.6. Si un servidor remoto envía un determinado encabezado de respuesta por medio de HTTP o HTTPS, ocurre una denegación de servicio. Este encabezado puede ocurrir plausiblemente en tráfico de red benigno"
    }
  ],
  "lastModified": "2026-06-17T03:46:43.673",
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}