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GHSA-GMQ5-QGC7-64GV

Vulnerability from github – Published: 2026-01-13 18:31 – Updated: 2026-03-25 21:30

Details

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

ipv6: fix a BUG in rt6_get_pcpu_route() under PREEMPT_RT

On PREEMPT_RT kernels, after rt6_get_pcpu_route() returns NULL, the current task can be preempted. Another task running on the same CPU may then execute rt6_make_pcpu_route() and successfully install a pcpu_rt entry. When the first task resumes execution, its cmpxchg() in rt6_make_pcpu_route() will fail because rt6i_pcpu is no longer NULL, triggering the BUG_ON(prev). It's easy to reproduce it by adding mdelay() after rt6_get_pcpu_route().

Using preempt_disable/enable is not appropriate here because ip6_rt_pcpu_alloc() may sleep.

Fix this by handling the cmpxchg() failure gracefully on PREEMPT_RT: free our allocation and return the existing pcpu_rt installed by another task. The BUG_ON is replaced by WARN_ON_ONCE for non-PREEMPT_RT kernels where such races should not occur.

Severity

5.5 (Medium)


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

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{
  "affected": [],
  "aliases": [
    "CVE-2025-71080"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-617"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-01-13T16:16:07Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: fix a BUG in rt6_get_pcpu_route() under PREEMPT_RT\n\nOn PREEMPT_RT kernels, after rt6_get_pcpu_route() returns NULL, the\ncurrent task can be preempted. Another task running on the same CPU\nmay then execute rt6_make_pcpu_route() and successfully install a\npcpu_rt entry. When the first task resumes execution, its cmpxchg()\nin rt6_make_pcpu_route() will fail because rt6i_pcpu is no longer\nNULL, triggering the BUG_ON(prev). It\u0027s easy to reproduce it by adding\nmdelay() after rt6_get_pcpu_route().\n\nUsing preempt_disable/enable is not appropriate here because\nip6_rt_pcpu_alloc() may sleep.\n\nFix this by handling the cmpxchg() failure gracefully on PREEMPT_RT:\nfree our allocation and return the existing pcpu_rt installed by\nanother task. The BUG_ON is replaced by WARN_ON_ONCE for non-PREEMPT_RT\nkernels where such races should not occur.",
  "id": "GHSA-gmq5-qgc7-64gv",
  "modified": "2026-03-25T21:30:21Z",
  "published": "2026-01-13T18:31:06Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-71080"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1adaea51c61b52e24e7ab38f7d3eba023b2d050d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1dc33ad0867325f8d2c6d7b2a6f542d4f3121f66"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/787515ccb2292f82eb0876993129154629a49651"
    }
  ],
  "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-2025-71080 (GCVE-0-2025-71080)

Vulnerability from cvelistv5 – Published: 2026-01-13 15:34 – Updated: 2026-08-05 12:11

Title

ipv6: fix a BUG in rt6_get_pcpu_route() under PREEMPT_RT

Summary

In the Linux kernel, the following vulnerability has been resolved: ipv6: fix a BUG in rt6_get_pcpu_route() under PREEMPT_RT On PREEMPT_RT kernels, after rt6_get_pcpu_route() returns NULL, the current task can be preempted. Another task running on the same CPU may then execute rt6_make_pcpu_route() and successfully install a pcpu_rt entry. When the first task resumes execution, its cmpxchg() in rt6_make_pcpu_route() will fail because rt6i_pcpu is no longer NULL, triggering the BUG_ON(prev). It's easy to reproduce it by adding mdelay() after rt6_get_pcpu_route(). Using preempt_disable/enable is not appropriate here because ip6_rt_pcpu_alloc() may sleep. Fix this by handling the cmpxchg() failure gracefully on PREEMPT_RT: free our allocation and return the existing pcpu_rt installed by another task. The BUG_ON is replaced by WARN_ON_ONCE for non-PREEMPT_RT kernels where such races should not occur.

Severity

7.5 (High)


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

Assigner

Linux mitre root Scorecard

References

3 references

URL	Tags
https://git.kernel.org/stable/c/1dc33ad0867325f8d…
https://git.kernel.org/stable/c/787515ccb2292f82e…
https://git.kernel.org/stable/c/1adaea51c61b52e24…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: d2d6422f8bd17c6bb205133e290625a564194496 , < 1dc33ad0867325f8d2c6d7b2a6f542d4f3121f66 (git) Affected: d2d6422f8bd17c6bb205133e290625a564194496 , < 787515ccb2292f82eb0876993129154629a49651 (git) Affected: d2d6422f8bd17c6bb205133e290625a564194496 , < 1adaea51c61b52e24e7ab38f7d3eba023b2d050d (git)
Linux	Linux	Affected: 6.12 Unaffected: 0 , < 6.12 (semver) Unaffected: 6.12.64 , ≤ 6.12.* (semver) Unaffected: 6.18.4 , ≤ 6.18.* (semver) Unaffected: 6.19 , ≤ * (original_commit_for_fix)

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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/route.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "1dc33ad0867325f8d2c6d7b2a6f542d4f3121f66",
              "status": "affected",
              "version": "d2d6422f8bd17c6bb205133e290625a564194496",
              "versionType": "git"
            },
            {
              "lessThan": "787515ccb2292f82eb0876993129154629a49651",
              "status": "affected",
              "version": "d2d6422f8bd17c6bb205133e290625a564194496",
              "versionType": "git"
            },
            {
              "lessThan": "1adaea51c61b52e24e7ab38f7d3eba023b2d050d",
              "status": "affected",
              "version": "d2d6422f8bd17c6bb205133e290625a564194496",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/ipv6/route.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.12"
            },
            {
              "lessThan": "6.12",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.64",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.4",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.19",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.64",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.4",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.19",
                  "versionStartIncluding": "6.12",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: fix a BUG in rt6_get_pcpu_route() under PREEMPT_RT\n\nOn PREEMPT_RT kernels, after rt6_get_pcpu_route() returns NULL, the\ncurrent task can be preempted. Another task running on the same CPU\nmay then execute rt6_make_pcpu_route() and successfully install a\npcpu_rt entry. When the first task resumes execution, its cmpxchg()\nin rt6_make_pcpu_route() will fail because rt6i_pcpu is no longer\nNULL, triggering the BUG_ON(prev). It\u0027s easy to reproduce it by adding\nmdelay() after rt6_get_pcpu_route().\n\nUsing preempt_disable/enable is not appropriate here because\nip6_rt_pcpu_alloc() may sleep.\n\nFix this by handling the cmpxchg() failure gracefully on PREEMPT_RT:\nfree our allocation and return the existing pcpu_rt installed by\nanother task. The BUG_ON is replaced by WARN_ON_ONCE for non-PREEMPT_RT\nkernels where such races should not occur."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - Unauthenticated IPv6 packets reach ip6_route_input() and ip6_pol_route() before transport delivery or authentication, exposing the vulnerable per-CPU route creation path to a remote peer.\nAC:L - In a reasonable multi-queue or threaded-network PREEMPT_RT deployment, concurrent attacker-driven packet streams can exercise both sides of the short empty-slot race repeatedly. No memory-layout guess or inherently uncontrollable condition is required.\nPR:N - The inbound IPv6 routing path performs no capability or authentication check before reaching the vulnerable code.\nUI:N - No victim action is required; processing attacker-generated IPv6 traffic triggers route lookup automatically.\nS:U - The resulting kernel failure affects the same host and security authority in which packet processing occurs, without crossing a virtualization or sandbox boundary.\nC:N - The failed cmpxchg only detects an already-installed valid route and immediately reaches BUG_ON; it provides no memory disclosure or read primitive.\nI:N - The atomic installation fails without overwriting the existing pointer, and there is no use-after-free, out-of-bounds write, or other attacker-controlled modification.\nA:H - BUG_ON executes while bottom halves are disabled and raises a fatal invalid-opcode oops, which can directly produce a kernel panic and complete system outage."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:11:55.485Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/787515ccb2292f82eb0876993129154629a49651"
        },
        {
          "url": "https://git.kernel.org/stable/c/1adaea51c61b52e24e7ab38f7d3eba023b2d050d"
        }
      ],
      "title": "ipv6: fix a BUG in rt6_get_pcpu_route() under PREEMPT_RT",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-71080",
    "datePublished": "2026-01-13T15:34:44.832Z",
    "dateReserved": "2026-01-13T15:30:19.648Z",
    "dateUpdated": "2026-08-05T12:11:55.485Z",
    "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.

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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GHSA-GMQ5-QGC7-64GV

CVE-2025-71080 (GCVE-0-2025-71080)

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