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CVE-2021-34556

Status: ModifiedMedium (5.5)—

In the Linux kernel through 5.13.7, an unprivileged BPF program can obtain sensitive information from kernel memory via a Speculative Store Bypass side-channel attack because the protection mechanism neglects the possibility of uninitialized memory locations on the BPF stack.

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 — FedoraLinux — Linux Kernel

CWEs

References

Raw JSON (NVD)

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  "id": "CVE-2021-34556",
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              "technicalImpact": "partial"
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          "version": "2.0.3",
          "timestamp": "2026-10-08T21:00:32.354615Z"
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          "vectorString": "AV:L/AC:L/Au:N/C:P/I:N/A:N",
          "authentication": "NONE",
          "integrityImpact": "NONE",
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          "availabilityImpact": "NONE",
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        "obtainAllPrivilege": false,
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    },
    {
      "lang": "es",
      "value": "En el kernel de Linux versiones hasta 5.13.7, un programa BPF sin privilegios puede obtener información confidencial de la memoria del kernel por medio de un ataque de canal lateral Omisión de Almacenamiento Especulativo porque el mecanismo de protección no tiene en cuenta la posibilidad de ubicaciones de memoria no inicializadas en la pila BPF"
    }
  ],
  "lastModified": "2026-10-08T21:17:35.903",
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