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CVE-2021-29155

Status: ModifiedMedium (5.5)—💥 PoC

An issue was discovered in the Linux kernel through 5.11.x. kernel/bpf/verifier.c performs undesirable out-of-bounds speculation on pointer arithmetic, leading to side-channel attacks that defeat Spectre mitigations and obtain sensitive information from kernel memory. Specifically, for sequences of pointer arithmetic operations, the pointer modification performed by the first operation is not correctly accounted for when restricting subsequent operations.

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).

💥 Public exploits

Exploit code or detection templates are publicly available. This is not the same as confirmed active exploitation (KEV), but it raises the risk: patch with priority.

⚠️ GitHub proofs of concept are not verified: some are fake or contain malware. Never run them outside an isolated lab.

Affected technologies (3)

Debian — Debian LinuxFedoraproject — FedoraLinux — Linux Kernel

CWEs

References

Raw JSON (NVD)

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          "lang": "en",
          "value": "CWE-125"
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      "value": "An issue was discovered in the Linux kernel through 5.11.x. kernel/bpf/verifier.c performs undesirable out-of-bounds speculation on pointer arithmetic, leading to side-channel attacks that defeat Spectre mitigations and obtain sensitive information from kernel memory. Specifically, for sequences of pointer arithmetic operations, the pointer modification performed by the first operation is not correctly accounted for when restricting subsequent operations."
    },
    {
      "lang": "es",
      "value": "Se detectó un problema en el kernel de Linux versiones hasta 5.11.x. En el archivo kernel/bpf/verifier.c lleva a cabo especulaciones indeseables fuera de límites en la aritmética de punteros, conllevando a ataques de canal lateral que anulan las mitigaciones de Spectre y consiguen información confidencial de la memoria del kernel. Específicamente, para secuencias de operaciones aritméticas de puntero, la modificación de puntero llevada a cabo por la primera operación no se contabiliza correctamente al restringir operaciones posteriores"
    }
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  "lastModified": "2026-06-17T03:47:22.490",
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