FKIE_CVE-2026-52943

Vulnerability from fkie_nvd - Published: 2026-06-24 10:17 - Updated: 2026-07-08 20:28
Severity
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: net: skbuff: fix missing zerocopy reference in pskb_carve helpers pskb_carve_inside_header() and pskb_carve_inside_nonlinear() both copy the old skb_shared_info header into a new buffer via memcpy(), which includes the destructor_arg pointer (uarg) for MSG_ZEROCOPY skbs. Neither function calls net_zcopy_get() for the new shinfo, creating an unaccounted holder: every skb_shared_info with destructor_arg set will call skb_zcopy_clear() once when freed, but the corresponding net_zcopy_get() was never called for the new copy. Repeated calls drive uarg->refcnt to zero prematurely, freeing ubuf_info_msgzc while TX skbs still hold live destructor_arg pointers. KASAN reports use-after-free on a freed ubuf_info_msgzc: BUG: KASAN: slab-use-after-free in skb_release_data+0x77b/0x810 Read of size 8 at addr ffff88801574d3e8 by task poc/220 Call Trace: skb_release_data+0x77b/0x810 kfree_skb_list_reason+0x13e/0x610 skb_release_data+0x4cd/0x810 sk_skb_reason_drop+0xf3/0x340 skb_queue_purge_reason+0x282/0x440 rds_tcp_inc_free+0x1e/0x30 rds_recvmsg+0x354/0x1780 __sys_recvmsg+0xdf/0x180 Allocated by task 219: msg_zerocopy_realloc+0x157/0x7b0 tcp_sendmsg_locked+0x2892/0x3ba0 Freed by task 219: ip_recv_error+0x74a/0xb10 tcp_recvmsg+0x475/0x530 The skb consuming the late access still referenced the same uarg via shinfo->destructor_arg copied by pskb_carve_inside_nonlinear() without a refcount bump. This has been verified to be reliably exploitable: a working proof-of-concept achieves full root privilege escalation from an unprivileged local user on a default kernel configuration. The fix follows the pattern of pskb_expand_head() which has the same memcpy/cloned structure. For pskb_carve_inside_header(), net_zcopy_get() is placed after skb_orphan_frags() succeeds, so the orphan error path needs no cleanup. For pskb_carve_inside_nonlinear(), net_zcopy_get() is placed after all failure points and just before skb_release_data(), so no error path needs cleanup at all -- matching pskb_expand_head() more closely and avoiding the need for a balancing net_zcopy_put().
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/2e0e74c59b2761a414d9f48d7bee1e45220b2427Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/474d6c771d798bca84f0a140b611e36743511e18Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/8dbed691e43a50903658130bde0fcb5abc425b37Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/96a4713ae041cc85e712bac682cd2e644004d6c6Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/98d0912e9f841e5529a5b89a972805f34cb1c69dPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/9b40bdc2a3298225dffab8158208a0d8c6300578Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/ceafb893b12f23331dcc5ff9587e643c3a40ee9fPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/fd470f0a97b8e9a125f520265d2f3b088ffb5b8aPatch
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://access.redhat.com/security/cve/CVE-2026-52943Third Party Advisory
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://bugzilla.redhat.com/show_bug.cgi?id=2492137Third Party Advisory
0b0ca135-0b70-47e7-9f44-1890c2a1c46chttps://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-52943.jsonThird Party Advisory
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel 7.1
linux linux_kernel 7.1
linux linux_kernel 7.1
linux linux_kernel 7.1
linux linux_kernel 7.1
To clipboard 

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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: skbuff: fix missing zerocopy reference in pskb_carve helpers\n\npskb_carve_inside_header() and pskb_carve_inside_nonlinear() both copy\nthe old skb_shared_info header into a new buffer via memcpy(), which\nincludes the destructor_arg pointer (uarg) for MSG_ZEROCOPY skbs.\nNeither function calls net_zcopy_get() for the new shinfo, creating an\nunaccounted holder: every skb_shared_info with destructor_arg set will\ncall skb_zcopy_clear() once when freed, but the corresponding\nnet_zcopy_get() was never called for the new copy. Repeated calls\ndrive uarg-\u003erefcnt to zero prematurely, freeing ubuf_info_msgzc while\nTX skbs still hold live destructor_arg pointers.\n\nKASAN reports use-after-free on a freed ubuf_info_msgzc:\n\n  BUG: KASAN: slab-use-after-free in skb_release_data+0x77b/0x810\n  Read of size 8 at addr ffff88801574d3e8 by task poc/220\n\n  Call Trace:\n   skb_release_data+0x77b/0x810\n   kfree_skb_list_reason+0x13e/0x610\n   skb_release_data+0x4cd/0x810\n   sk_skb_reason_drop+0xf3/0x340\n   skb_queue_purge_reason+0x282/0x440\n   rds_tcp_inc_free+0x1e/0x30\n   rds_recvmsg+0x354/0x1780\n   __sys_recvmsg+0xdf/0x180\n\n  Allocated by task 219:\n   msg_zerocopy_realloc+0x157/0x7b0\n   tcp_sendmsg_locked+0x2892/0x3ba0\n\n  Freed by task 219:\n   ip_recv_error+0x74a/0xb10\n   tcp_recvmsg+0x475/0x530\n\nThe skb consuming the late access still referenced the same uarg via\nshinfo-\u003edestructor_arg copied by pskb_carve_inside_nonlinear() without\na refcount bump. This has been verified to be reliably exploitable: a\nworking proof-of-concept achieves full root privilege escalation from\nan unprivileged local user on a default kernel configuration.\n\nThe fix follows the pattern of pskb_expand_head() which has the same\nmemcpy/cloned structure. For pskb_carve_inside_header(), net_zcopy_get()\nis placed after skb_orphan_frags() succeeds, so the orphan error path\nneeds no cleanup. For pskb_carve_inside_nonlinear(), net_zcopy_get() is\nplaced after all failure points and just before skb_release_data(), so\nno error path needs cleanup at all -- matching pskb_expand_head() more\nclosely and avoiding the need for a balancing net_zcopy_put()."
    }
  ],
  "id": "CVE-2026-52943",
  "lastModified": "2026-07-08T20:28:57.453",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "type": "Secondary"
      },
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
        "type": "Secondary"
      }
    ]
  },
  "published": "2026-06-24T10:17:19.293",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
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      "url": "https://git.kernel.org/stable/c/2e0e74c59b2761a414d9f48d7bee1e45220b2427"
    },
    {
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    },
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      "tags": [
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      "url": "https://git.kernel.org/stable/c/fd470f0a97b8e9a125f520265d2f3b088ffb5b8a"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "tags": [
        "Third Party Advisory"
      ],
      "url": "https://access.redhat.com/security/cve/CVE-2026-52943"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "tags": [
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      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2492137"
    },
    {
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "tags": [
        "Third Party Advisory"
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      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-52943.json"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-416"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    },
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-911"
        }
      ],
      "source": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
      "type": "Secondary"
    }
  ]
}



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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

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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.
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  • 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.