FKIE_CVE-2025-71080
Vulnerability from fkie_nvd - Published: 2026-01-13 16:16 - Updated: 2026-03-25 19:42
Severity
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.
References
Impacted products
| Vendor | Product | Version | |
|---|---|---|---|
| linux | linux_kernel | * | |
| linux | linux_kernel | * | |
| linux | linux_kernel | 6.12 | |
| linux | linux_kernel | 6.19 | |
| linux | linux_kernel | 6.19 | |
| linux | linux_kernel | 6.19 | |
| linux | linux_kernel | 6.19 | |
| linux | linux_kernel | 6.19 | |
| linux | linux_kernel | 6.19 | |
| linux | linux_kernel | 6.19 | |
| linux | linux_kernel | 6.19 |
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"cveTags": [],
"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."
},
{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nipv6: corregir un BUG en rt6_get_pcpu_route() bajo PREEMPT_RT\n\nEn kernels PREEMPT_RT, despu\u00e9s de que rt6_get_pcpu_route() devuelve NULL, la tarea actual puede ser desalojada. Otra tarea ejecut\u00e1ndose en la misma CPU puede entonces ejecutar rt6_make_pcpu_route() e instalar exitosamente una entrada pcpu_rt. Cuando la primera tarea reanuda la ejecuci\u00f3n, su cmpxchg() en rt6_make_pcpu_route() fallar\u00e1 porque rt6i_pcpu ya no es NULL, lo que activa el BUG_ON(prev). Es f\u00e1cil reproducirlo a\u00f1adiendo mdelay() despu\u00e9s de rt6_get_pcpu_route().\n\nUsar preempt_disable/enable no es apropiado aqu\u00ed porque ip6_rt_pcpu_alloc() puede dormir.\n\nSolucionar esto manejando el fallo de cmpxchg() de forma elegante en PREEMPT_RT: liberar nuestra asignaci\u00f3n y devolver el pcpu_rt existente instalado por otra tarea. El BUG_ON es reemplazado por WARN_ON_ONCE para kernels que no son PREEMPT_RT donde tales condiciones de carrera no deber\u00edan ocurrir."
}
],
"id": "CVE-2025-71080",
"lastModified": "2026-03-25T19:42:22.610",
"metrics": {
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{
"cvssData": {
"attackComplexity": "LOW",
"attackVector": "LOCAL",
"availabilityImpact": "HIGH",
"baseScore": 5.5,
"baseSeverity": "MEDIUM",
"confidentialityImpact": "NONE",
"integrityImpact": "NONE",
"privilegesRequired": "LOW",
"scope": "UNCHANGED",
"userInteraction": "NONE",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"version": "3.1"
},
"exploitabilityScore": 1.8,
"impactScore": 3.6,
"source": "nvd@nist.gov",
"type": "Primary"
}
]
},
"published": "2026-01-13T16:16:07.550",
"references": [
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"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"tags": [
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"url": "https://git.kernel.org/stable/c/1adaea51c61b52e24e7ab38f7d3eba023b2d050d"
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"vulnStatus": "Analyzed",
"weaknesses": [
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"description": [
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"lang": "en",
"value": "CWE-617"
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"source": "nvd@nist.gov",
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
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.
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