Vulnerability-Lookup

GHSA-Q44J-P422-QJH5

Vulnerability from github – Published: 2025-08-16 12:30 – Updated: 2026-01-07 21:31

Details

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.

Severity

5.5 (Medium)


                  
                    CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Show details on source website

JSON

To clipboard

{
  "affected": [],
  "aliases": [
    "CVE-2025-38528"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-08-16T12:15:28Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject %p% format string in bprintf-like helpers\n\nstatic const char fmt[] = \"%p%\";\n    bpf_trace_printk(fmt, sizeof(fmt));\n\nThe above BPF program isn\u0027t rejected and causes a kernel warning at\nruntime:\n\n    Please remove unsupported %\\x00 in format string\n    WARNING: CPU: 1 PID: 7244 at lib/vsprintf.c:2680 format_decode+0x49c/0x5d0\n\nThis happens because bpf_bprintf_prepare skips over the second %,\ndetected as punctuation, while processing %p. This patch fixes it by\nnot skipping over punctuation. %\\x00 is then processed in the next\niteration and rejected.",
  "id": "GHSA-q44j-p422-qjh5",
  "modified": "2026-01-07T21:31:37Z",
  "published": "2025-08-16T12:30:32Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38528"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1c5f5fd47bbda17cb885fe6f03730702cd53d3f8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/61d5fa45ed13e42af14c7e959baba9908b8ee6d4"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6952aeace93f8c9ea01849efecac24dd3152c9c9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/97303e541e12f1fea97834ec64b98991e8775f39"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e7be679124bae8cf4fa6e40d7e1661baddfb3289"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f8242745871f81a3ac37f9f51853d12854fd0b58"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2025-38528 (GCVE-0-2025-38528)

Vulnerability from cvelistv5 – Published: 2025-08-16 11:12 – Updated: 2026-08-05 12:02

Title

bpf: Reject %p% format string in bprintf-like helpers

Summary

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.

Severity

7.1 (High)


                        
                          CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H

Assigner

Linux mitre root

References

7 references

URL	Tags
https://git.kernel.org/stable/c/97303e541e12f1fea…
https://git.kernel.org/stable/c/61d5fa45ed13e42af…
https://git.kernel.org/stable/c/e7be679124bae8cf4…
https://git.kernel.org/stable/c/6952aeace93f8c9ea…
https://git.kernel.org/stable/c/1c5f5fd47bbda17cb…
https://git.kernel.org/stable/c/f8242745871f81a3a…
https://lists.debian.org/debian-lts-announce/2025…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 48cac3f4a96ddf08df8e53809ed066de0dc93915 , < 97303e541e12f1fea97834ec64b98991e8775f39 (git) Affected: 48cac3f4a96ddf08df8e53809ed066de0dc93915 , < 61d5fa45ed13e42af14c7e959baba9908b8ee6d4 (git) Affected: 48cac3f4a96ddf08df8e53809ed066de0dc93915 , < e7be679124bae8cf4fa6e40d7e1661baddfb3289 (git) Affected: 48cac3f4a96ddf08df8e53809ed066de0dc93915 , < 6952aeace93f8c9ea01849efecac24dd3152c9c9 (git) Affected: 48cac3f4a96ddf08df8e53809ed066de0dc93915 , < 1c5f5fd47bbda17cb885fe6f03730702cd53d3f8 (git) Affected: 48cac3f4a96ddf08df8e53809ed066de0dc93915 , < f8242745871f81a3ac37f9f51853d12854fd0b58 (git)
Linux	Linux	Affected: 5.13 Unaffected: 0 , < 5.13 (semver) Unaffected: 5.15.190 , ≤ 5.15.* (semver) Unaffected: 6.1.147 , ≤ 6.1.* (semver) Unaffected: 6.6.100 , ≤ 6.6.* (semver) Unaffected: 6.12.40 , ≤ 6.12.* (semver) Unaffected: 6.15.8 , ≤ 6.15.* (semver) Unaffected: 6.16 , ≤ * (original_commit_for_fix)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2025-11-03T17:39:24.864Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "url": "https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/helpers.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "97303e541e12f1fea97834ec64b98991e8775f39",
              "status": "affected",
              "version": "48cac3f4a96ddf08df8e53809ed066de0dc93915",
              "versionType": "git"
            },
            {
              "lessThan": "61d5fa45ed13e42af14c7e959baba9908b8ee6d4",
              "status": "affected",
              "version": "48cac3f4a96ddf08df8e53809ed066de0dc93915",
              "versionType": "git"
            },
            {
              "lessThan": "e7be679124bae8cf4fa6e40d7e1661baddfb3289",
              "status": "affected",
              "version": "48cac3f4a96ddf08df8e53809ed066de0dc93915",
              "versionType": "git"
            },
            {
              "lessThan": "6952aeace93f8c9ea01849efecac24dd3152c9c9",
              "status": "affected",
              "version": "48cac3f4a96ddf08df8e53809ed066de0dc93915",
              "versionType": "git"
            },
            {
              "lessThan": "1c5f5fd47bbda17cb885fe6f03730702cd53d3f8",
              "status": "affected",
              "version": "48cac3f4a96ddf08df8e53809ed066de0dc93915",
              "versionType": "git"
            },
            {
              "lessThan": "f8242745871f81a3ac37f9f51853d12854fd0b58",
              "status": "affected",
              "version": "48cac3f4a96ddf08df8e53809ed066de0dc93915",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "kernel/bpf/helpers.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "5.13"
            },
            {
              "lessThan": "5.13",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.190",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.147",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.100",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.40",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.15.*",
              "status": "unaffected",
              "version": "6.15.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.16",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "5.15.190",
                  "versionStartIncluding": "5.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.1.147",
                  "versionStartIncluding": "5.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.100",
                  "versionStartIncluding": "5.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.40",
                  "versionStartIncluding": "5.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.15.8",
                  "versionStartIncluding": "5.13",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.16",
                  "versionStartIncluding": "5.13",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject %p% format string in bprintf-like helpers\n\nstatic const char fmt[] = \"%p%\";\n    bpf_trace_printk(fmt, sizeof(fmt));\n\nThe above BPF program isn\u0027t rejected and causes a kernel warning at\nruntime:\n\n    Please remove unsupported %\\x00 in format string\n    WARNING: CPU: 1 PID: 7244 at lib/vsprintf.c:2680 format_decode+0x49c/0x5d0\n\nThis happens because bpf_bprintf_prepare skips over the second %,\ndetected as punctuation, while processing %p. This patch fixes it by\nnot skipping over punctuation. %\\x00 is then processed in the next\niteration and rejected."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - The only trigger is a locally loaded eBPF program invoking a bprintf-like helper (`bpf_trace_printk`, `bpf_trace_vprintk`, `bpf_snprintf`, `bpf_seq_printf`) via the `bpf()` syscall; the format string is attacker-authored at `BPF_PROG_LOAD` time and consumed in the calling task\u0027s own context. No remote peer or packet can supply a format string.\nAC:L - The attacker fully controls the constant format string, so `\"%p%\"` deterministically reaches the `WARN_ONCE` in `format_decode()` and `\"%p%s\"` deterministically desyncs `bpf_bprintf_prepare()` from `bstr_printf()` on the first call \u2014 no race, no timing window, no dependence on memory layout the attacker cannot influence.\nPR:L - Reaching the helpers requires CAP_BPF plus CAP_PERFMON (or CAP_SYS_ADMIN) rather than full root, and these are routinely granted to non-root eBPF observability/profiling service accounts and can be delegated into a user namespace via a BPF token (supported in all affected 6.9+ branches), so a low-privilege non-root actor suffices.\nUI:N - The attacker performs self-contained `bpf(BPF_PROG_LOAD)` and program-run/attach operations; no victim must mount a filesystem, open a file, or take any other action.\nS:U - The faulty parse, the warning, and the stale-memory read all occur in the kernel\u0027s own security authority within the calling task\u0027s context; no hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - The prepare/print desync makes `bstr_printf()`\u0027s `FORMAT_STATE_STR` `strlen()` and copy uninitialized bytes from the per-CPU `bpf_bprintf_buffers` (512-byte `bin_args` followed by the 1024-byte `buf`, and potentially past the struct into adjacent per-CPU memory) straight into the `bpf_snprintf` output buffer or trace ring buffer that the attacker reads; because `nocopy_fmt` stores raw unhashed 64-bit values there, this leaks unsanitized kernel pointers, on top of the KASLR-defeating backtrace the `WARN_ONCE` dumps to dmesg.\nI:N - All writes stay bounded \u2014 `nocopy_fmt` checks `tmp_buf_end - tmp_buf` before storing, and `bstr_printf()`/`string()` gate every store on `str \u003c end` \u2014 so the bug under-fills the argument buffer rather than overflowing it; no kernel or user memory is modified out of bounds.\nA:H - `\"%p%\"` triggers `WARN_ONCE` at `lib/vsprintf.c:2807`, which becomes a full kernel panic on the widely deployed `panic_on_warn=1` used in hardened cloud, Android, and fuzzing configurations \u2014 exactly the crash syzbot reported \u2014 and the unbounded `strlen()` over per-CPU memory can additionally fault; even without `panic_on_warn` the splat taints the kernel and can trip health-check tooling into taking the node down."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:02:41.331Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/97303e541e12f1fea97834ec64b98991e8775f39"
        },
        {
          "url": "https://git.kernel.org/stable/c/61d5fa45ed13e42af14c7e959baba9908b8ee6d4"
        },
        {
          "url": "https://git.kernel.org/stable/c/e7be679124bae8cf4fa6e40d7e1661baddfb3289"
        },
        {
          "url": "https://git.kernel.org/stable/c/6952aeace93f8c9ea01849efecac24dd3152c9c9"
        },
        {
          "url": "https://git.kernel.org/stable/c/1c5f5fd47bbda17cb885fe6f03730702cd53d3f8"
        },
        {
          "url": "https://git.kernel.org/stable/c/f8242745871f81a3ac37f9f51853d12854fd0b58"
        }
      ],
      "title": "bpf: Reject %p% format string in bprintf-like helpers",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-38528",
    "datePublished": "2025-08-16T11:12:21.667Z",
    "dateReserved": "2025-04-16T04:51:24.023Z",
    "dateUpdated": "2026-08-05T12:02:41.331Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.