bpf: Reject rdonly/rdwr_buf_size kfunc arguments that exceed u32 max
CVE-2026-93125 · published 17 Sept 2026
How serious is it
- Severity: high, CVSS score 7.8 out of 10.
- No exploit prediction (EPSS) score yet.
- Not on the CISA list of exploited vulnerabilities.
- No public exploit in Exploit-DB.
Is your app affected by CVE-2026-93125?
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Who is affected
- Linux Linux: eb1f7f71c126c8fd50ea81af98f97c4b581ea4ae to < 2147065d3a4e1d5d42ae553fef165f17ec5e0e79, eb1f7f71c126c8fd50ea81af98f97c4b581ea4ae to < b6ac0b5732047d43172b9dfbe6b57b9b8de303c2, eb1f7f71c126c8fd50ea81af98f97c4b581ea4ae to < 93a20b14f8627b2d3486e3ec1d3f2e7275a506ec, eb1f7f71c126c8fd50ea81af98f97c4b581ea4ae to < 56a3846830ac95a472297d0cbba75cbff29540bb
- Linux Linux: 6.1
How to check
- Find out whether you run the affected product and which version, then compare it with the versions above.
How to fix
Copies a prompt for Claude Code, Cursor or Codex that asks it to check whether you run this product.
- Apply the vendor's update or mitigation from the references below. If there is none yet, limit exposure of the affected service until there is.
- If a vulnerable version was live, check your logs and rotate the secrets that server could read.
The advisory
In the Linux kernel, the following vulnerability has been resolved:
bpf: Reject rdonly/rdwr_buf_size kfunc arguments that exceed u32 max
check_kfunc_args() detects a kfunc argument named rdonly_buf_size or
rdwr_buf_size and stores reg->var_off.value into meta->r0_size, a u64,
and does not bound it. check_kfunc_call() later copies that value into
the returned register's mem_size field:
meta->r0_size = reg->var_off.value;
...
regs[BPF_REG_0].mem_size = meta.r0_size;
regs[BPF_REG_0].mem_size is u32. A constant whose upper 32 bits are set
gets truncated instead of causing a load-time rejection, so the verifier
records a PTR_TO_MEM register with an approximately 4 GiB mem_size for
whatever allocation the kfunc returned. A later access check against
that register uses the truncated, wrong bound.
Reject rdonly_buf_size/rdwr_buf_size values that exceed U32_MAX at the
point meta->r0_size is set.
Check your whole app
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References
- git.kernel.org/stable/c/2147065d3a4e1d5d42ae553fef165f17ec5e0e79
- git.kernel.org/stable/c/b6ac0b5732047d43172b9dfbe6b57b9b8de303c2
- git.kernel.org/stable/c/93a20b14f8627b2d3486e3ec1d3f2e7275a506ec
- git.kernel.org/stable/c/56a3846830ac95a472297d0cbba75cbff29540bb
- git.kernel.org/stable/c/2aaf67f0516fde29620d0edfc29c01b9ea7ad430
Merged from CVE List. Last updated 26 Oct 2026. All vulnerabilities · RSS · JSON