Vulnerability Database

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Total vulnerabilities in the database

CVE-2025-39917 — linux / linux_kernel

Out-of-bounds Write

In the Linux kernel, the following vulnerability has been resolved:

bpf: Fix out-of-bounds dynptr write in bpf_crypto_crypt

Stanislav reported that in bpf_crypto_crypt() the destination dynptr's size is not validated to be at least as large as the source dynptr's size before calling into the crypto backend with 'len = src_len'. This can result in an OOB write when the destination is smaller than the source.

Concretely, in mentioned function, psrc and pdst are both linear buffers fetched from each dynptr:

psrc = __bpf_dynptr_data(src, src_len); [...] pdst = __bpf_dynptr_data_rw(dst, dst_len); [...] err = decrypt ? ctx->type->decrypt(ctx->tfm, psrc, pdst, src_len, piv) : ctx->type->encrypt(ctx->tfm, psrc, pdst, src_len, piv);

The crypto backend expects pdst to be large enough with a src_len length that can be written. Add an additional src_len > dst_len check and bail out if it's the case. Note that these kfuncs are accessible under root privileges only.

  • Published: Oct 1, 2025
  • Updated: Dec 15, 2025
  • CVE: CVE-2025-39917
  • Severity: High
  • Exploit:
  • CISA KEV:

CVSS v3:

  • Severity: High
  • Score: 7.8
  • AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CWEs:

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