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GHSA-9HQ9-GV35-C42W

Vulnerability from github – Published: 2025-05-09 09:33 – Updated: 2025-11-12 21:31

Details

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

9p/net: fix improper handling of bogus negative read/write replies

In p9_client_write() and p9_client_read_once(), if the server incorrectly replies with success but a negative write/read count then we would consider written (negative) <= rsize (positive) because both variables were signed.

Make variables unsigned to avoid this problem.

The reproducer linked below now fails with the following error instead of a null pointer deref: 9pnet: bogus RWRITE count (4294967295 > 3)

Severity

7.1 (High)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2025-37879"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-125"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-05-09T07:16:09Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\n9p/net: fix improper handling of bogus negative read/write replies\n\nIn p9_client_write() and p9_client_read_once(), if the server\nincorrectly replies with success but a negative write/read count then we\nwould consider written (negative) \u003c= rsize (positive) because both\nvariables were signed.\n\nMake variables unsigned to avoid this problem.\n\nThe reproducer linked below now fails with the following error instead\nof a null pointer deref:\n9pnet: bogus RWRITE count (4294967295 \u003e 3)",
  "id": "GHSA-9hq9-gv35-c42w",
  "modified": "2025-11-12T21:31:03Z",
  "published": "2025-05-09T09:33:20Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-37879"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/374e4cd75617c8c2552f562f39dd989583f5c330"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/468ff4a7c61fb811c596a7c44b6a5455e40fd12b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a68768e280b7d0c967ea509e791bb9b90adc94a5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c548f95688e2b5ae0e2ae43d53cf717156c7d034"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d0259a856afca31d699b706ed5e2adf11086c73b"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}

CVE-2025-37879 (GCVE-0-2025-37879)

Vulnerability from cvelistv5 – Published: 2025-05-09 06:45 – Updated: 2026-08-05 11:58

Title

9p/net: fix improper handling of bogus negative read/write replies

Summary

In the Linux kernel, the following vulnerability has been resolved: 9p/net: fix improper handling of bogus negative read/write replies In p9_client_write() and p9_client_read_once(), if the server incorrectly replies with success but a negative write/read count then we would consider written (negative) <= rsize (positive) because both variables were signed. Make variables unsigned to avoid this problem. The reproducer linked below now fails with the following error instead of a null pointer deref: 9pnet: bogus RWRITE count (4294967295 > 3)

Severity

9.8 (Critical)


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

Assigner

Linux mitre root

References

6 references

URL	Tags
https://git.kernel.org/stable/c/468ff4a7c61fb811c…
https://git.kernel.org/stable/c/a68768e280b7d0c96…
https://git.kernel.org/stable/c/c548f95688e2b5ae0…
https://git.kernel.org/stable/c/374e4cd75617c8c25…
https://git.kernel.org/stable/c/d0259a856afca31d6…
https://lists.debian.org/debian-lts-announce/2025…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 070b3656cf228eaaef7b28b59264c5c7cdbdd0fb , < 468ff4a7c61fb811c596a7c44b6a5455e40fd12b (git) Affected: 070b3656cf228eaaef7b28b59264c5c7cdbdd0fb , < a68768e280b7d0c967ea509e791bb9b90adc94a5 (git) Affected: 070b3656cf228eaaef7b28b59264c5c7cdbdd0fb , < c548f95688e2b5ae0e2ae43d53cf717156c7d034 (git) Affected: 070b3656cf228eaaef7b28b59264c5c7cdbdd0fb , < 374e4cd75617c8c2552f562f39dd989583f5c330 (git) Affected: 070b3656cf228eaaef7b28b59264c5c7cdbdd0fb , < d0259a856afca31d699b706ed5e2adf11086c73b (git)
Linux	Linux	Affected: 4.1 Unaffected: 0 , < 4.1 (semver) Unaffected: 6.1.136 , ≤ 6.1.* (semver) Unaffected: 6.6.89 , ≤ 6.6.* (semver) Unaffected: 6.12.26 , ≤ 6.12.* (semver) Unaffected: 6.14.5 , ≤ 6.14.* (semver) Unaffected: 6.15 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "adp": [
      {
        "providerMetadata": {
          "dateUpdated": "2025-11-03T19:56:51.125Z",
          "orgId": "af854a3a-2127-422b-91ae-364da2661108",
          "shortName": "CVE"
        },
        "references": [
          {
            "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"
          }
        ],
        "title": "CVE Program Container"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
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            },
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            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
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              "version": "6.6.89",
              "versionType": "semver"
            },
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              "versionType": "semver"
            },
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              "version": "6.14.5",
              "versionType": "semver"
            },
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              "status": "unaffected",
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      ],
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                  "versionStartIncluding": "4.1",
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                },
                {
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                },
                {
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\n9p/net: fix improper handling of bogus negative read/write replies\n\nIn p9_client_write() and p9_client_read_once(), if the server\nincorrectly replies with success but a negative write/read count then we\nwould consider written (negative) \u003c= rsize (positive) because both\nvariables were signed.\n\nMake variables unsigned to avoid this problem.\n\nThe reproducer linked below now fails with the following error instead\nof a null pointer deref:\n9pnet: bogus RWRITE count (4294967295 \u003e 3)"
        }
      ],
      "metrics": [
        {
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            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The attacker is the remote 9p file server, reachable over the TCP transport (`p9_fd_create_tcp`, port 564) or RDMA; 9p is unauthenticated and unencrypted on the wire, so a malicious server or an on-path MITM can inject the bogus RWRITE reply. The same primitive is available to a malicious hypervisor backend over virtio/Xen.\nAC:L - The server simply answers any TWRITE with a success reply carrying count 0xFFFFFFFF, deterministically bypassing the signed `rsize \u003c written` check. There is no race, no timing window, and no dependence on memory layout to reach the corruption.\nPR:N - The malicious 9p server is a remote peer holding no credentials or account on the victim client; 9p mounts commonly use auth=none, and an on-path attacker needs nothing at all. The mount being present is an environmental precondition, not a privilege held by the attacker.\nUI:N - On an already-mounted 9p share the bug fires on ordinary I/O, including kernel-initiated page-cache writeback via `v9fs_issue_write`, with no victim action required. No specific human interaction beyond the pre-existing mount configuration is needed.\nS:U - The corruption is confined to the 9p client kernel that parsed the reply, with no crossing into a different security authority such as a hypervisor or IOMMU boundary. Impact stays within the victim kernel\u0027s own scope.\nC:H - The over-revert leaves `i-\u003ebvec`/`i-\u003e__iov` pointing before the start of the bio_vec/kvec array, and because `p9_client_write()` keeps looping the next TWRITE marshals data from that out-of-bounds descriptor \u2014 sending adjacent kernel heap or stack memory straight to the attacker-controlled server. This is a repeatable kernel memory disclosure primitive.\nI:H - The same out-of-bounds iterator descriptor supplies attacker-uncontrolled `bv_page`/`iov_base` pointers used for subsequent copies, giving out-of-bounds kernel memory access leveragable for control-flow hijack. Additionally `offset += written` sign-extends the negative count into the u64 file offset and `total` goes negative, corrupting file data placement and netfs transfer accounting.\nA:H - The reported and reproduced result is a NULL pointer dereference in `iov_iter_folioq_revert()` when `folioq-\u003eprev` is NULL at the queue head, and `ITER_UBUF`/`ITER_XARRAY` hit an explicit `BUG()` in `iov_iter_revert()`. The write loop also never terminates because `i-\u003ecount` grows by one each iteration, hanging the task."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T11:58:00.365Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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          "url": "https://git.kernel.org/stable/c/374e4cd75617c8c2552f562f39dd989583f5c330"
        },
        {
          "url": "https://git.kernel.org/stable/c/d0259a856afca31d699b706ed5e2adf11086c73b"
        }
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      "title": "9p/net: fix improper handling of bogus negative read/write replies",
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    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-37879",
    "datePublished": "2025-05-09T06:45:43.197Z",
    "dateReserved": "2025-04-16T04:51:23.962Z",
    "dateUpdated": "2026-08-05T11:58:00.365Z",
    "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.

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