CVE-2026-52943 (GCVE-0-2026-52943)
Vulnerability from cvelistv5 – Published: 2026-06-24 09:00 – Updated: 2026-06-30 12:09
VLAI?
Title
net: skbuff: fix missing zerocopy reference in pskb_carve helpers
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().
Severity ?
7.8 (High)
CWE
- CWE-911 - Improper Update of Reference Count
Assigner
References
Impacted products
| Vendor | Product | Version | |||||||
|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux |
Affected:
6fa01ccd883021105e9f8af7d04b9f156fa3494a , < 8dbed691e43a50903658130bde0fcb5abc425b37
(git)
Affected: 6fa01ccd883021105e9f8af7d04b9f156fa3494a , < 9b40bdc2a3298225dffab8158208a0d8c6300578 (git) Affected: 6fa01ccd883021105e9f8af7d04b9f156fa3494a , < fd470f0a97b8e9a125f520265d2f3b088ffb5b8a (git) Affected: 6fa01ccd883021105e9f8af7d04b9f156fa3494a , < ceafb893b12f23331dcc5ff9587e643c3a40ee9f (git) Affected: 6fa01ccd883021105e9f8af7d04b9f156fa3494a , < 2e0e74c59b2761a414d9f48d7bee1e45220b2427 (git) Affected: 6fa01ccd883021105e9f8af7d04b9f156fa3494a , < 96a4713ae041cc85e712bac682cd2e644004d6c6 (git) Affected: 6fa01ccd883021105e9f8af7d04b9f156fa3494a , < 474d6c771d798bca84f0a140b611e36743511e18 (git) Affected: 6fa01ccd883021105e9f8af7d04b9f156fa3494a , < 98d0912e9f841e5529a5b89a972805f34cb1c69d (git) |
|||||||
|
|||||||||
{
"containers": {
"adp": [
{
"affected": [
{
"cpes": [
"cpe:/o:redhat:enterprise_linux:10"
],
"defaultStatus": "unaffected",
"product": "Red Hat Enterprise Linux 10",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/o:redhat:enterprise_linux:6"
],
"defaultStatus": "unaffected",
"product": "Red Hat Enterprise Linux 6",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/o:redhat:enterprise_linux:7"
],
"defaultStatus": "unaffected",
"product": "Red Hat Enterprise Linux 7",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/o:redhat:enterprise_linux:8"
],
"defaultStatus": "unaffected",
"product": "Red Hat Enterprise Linux 8",
"vendor": "Red Hat"
},
{
"cpes": [
"cpe:/o:redhat:enterprise_linux:9"
],
"defaultStatus": "unaffected",
"product": "Red Hat Enterprise Linux 9",
"vendor": "Red Hat"
}
],
"datePublic": "2026-06-24T00:00:00.000Z",
"descriptions": [
{
"lang": "en",
"value": "A flaw was found in the Linux kernel. The `pskb_carve_inside_header()` and `pskb_carve_inside_nonlinear()` helper functions, which handle network packet buffers, do not correctly account for zero-copy references. This oversight can lead to a use-after-free vulnerability, where memory is prematurely released while still in use. A local unprivileged user can exploit this flaw to achieve full root privilege escalation on the system."
}
],
"metrics": [
{
"other": {
"content": {
"namespace": "https://access.redhat.com/security/updates/classification/",
"value": "Important"
},
"type": "Red Hat severity rating"
}
},
{
"cvssV3_1": {
"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"
},
"format": "CVSS"
}
],
"problemTypes": [
{
"descriptions": [
{
"cweId": "CWE-911",
"description": "Improper Update of Reference Count",
"lang": "en",
"type": "CWE"
}
]
}
],
"providerMetadata": {
"dateUpdated": "2026-06-30T12:09:45.796Z",
"orgId": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c",
"shortName": "redhat-SADP"
},
"references": [
{
"tags": [
"vdb-entry",
"x_refsource_REDHAT"
],
"url": "https://access.redhat.com/security/cve/CVE-2026-52943"
},
{
"name": "RHBZ#2492137",
"tags": [
"issue-tracking",
"x_refsource_REDHAT"
],
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2492137"
},
{
"tags": [
"x_sadp-csaf-vex"
],
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-52943.json"
}
],
"timeline": [
{
"lang": "en",
"time": "2026-06-24T00:00:00.000Z",
"value": "Reported to Red Hat."
},
{
"lang": "en",
"time": "2026-06-24T00:00:00.000Z",
"value": "Made public."
}
],
"title": "kernel: net: skbuff: fix missing zerocopy reference in pskb_carve helpers",
"x_adpType": "supplier",
"x_generator": {
"engine": "sadp-cli 1.0.0"
}
}
],
"cna": {
"affected": [
{
"defaultStatus": "unaffected",
"product": "Linux",
"programFiles": [
"net/core/skbuff.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"lessThan": "8dbed691e43a50903658130bde0fcb5abc425b37",
"status": "affected",
"version": "6fa01ccd883021105e9f8af7d04b9f156fa3494a",
"versionType": "git"
},
{
"lessThan": "9b40bdc2a3298225dffab8158208a0d8c6300578",
"status": "affected",
"version": "6fa01ccd883021105e9f8af7d04b9f156fa3494a",
"versionType": "git"
},
{
"lessThan": "fd470f0a97b8e9a125f520265d2f3b088ffb5b8a",
"status": "affected",
"version": "6fa01ccd883021105e9f8af7d04b9f156fa3494a",
"versionType": "git"
},
{
"lessThan": "ceafb893b12f23331dcc5ff9587e643c3a40ee9f",
"status": "affected",
"version": "6fa01ccd883021105e9f8af7d04b9f156fa3494a",
"versionType": "git"
},
{
"lessThan": "2e0e74c59b2761a414d9f48d7bee1e45220b2427",
"status": "affected",
"version": "6fa01ccd883021105e9f8af7d04b9f156fa3494a",
"versionType": "git"
},
{
"lessThan": "96a4713ae041cc85e712bac682cd2e644004d6c6",
"status": "affected",
"version": "6fa01ccd883021105e9f8af7d04b9f156fa3494a",
"versionType": "git"
},
{
"lessThan": "474d6c771d798bca84f0a140b611e36743511e18",
"status": "affected",
"version": "6fa01ccd883021105e9f8af7d04b9f156fa3494a",
"versionType": "git"
},
{
"lessThan": "98d0912e9f841e5529a5b89a972805f34cb1c69d",
"status": "affected",
"version": "6fa01ccd883021105e9f8af7d04b9f156fa3494a",
"versionType": "git"
}
]
},
{
"defaultStatus": "affected",
"product": "Linux",
"programFiles": [
"net/core/skbuff.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"versions": [
{
"status": "affected",
"version": "4.7"
},
{
"lessThan": "4.7",
"status": "unaffected",
"version": "0",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.10.*",
"status": "unaffected",
"version": "5.10.259",
"versionType": "semver"
},
{
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"version": "5.15.210",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"version": "6.1.176",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"version": "6.6.143",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.12.*",
"status": "unaffected",
"version": "6.12.93",
"versionType": "semver"
},
{
"lessThanOrEqual": "6.18.*",
"status": "unaffected",
"version": "6.18.35",
"versionType": "semver"
},
{
"lessThanOrEqual": "7.0.*",
"status": "unaffected",
"version": "7.0.12",
"versionType": "semver"
},
{
"lessThanOrEqual": "*",
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix"
}
]
}
],
"cpeApplicability": [
{
"nodes": [
{
"cpeMatch": [
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.10.259",
"versionStartIncluding": "4.7",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "5.15.210",
"versionStartIncluding": "4.7",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.1.176",
"versionStartIncluding": "4.7",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.6.143",
"versionStartIncluding": "4.7",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.12.93",
"versionStartIncluding": "4.7",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "6.18.35",
"versionStartIncluding": "4.7",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.0.12",
"versionStartIncluding": "4.7",
"vulnerable": true
},
{
"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
"versionEndExcluding": "7.1",
"versionStartIncluding": "4.7",
"vulnerable": true
}
],
"negate": false,
"operator": "OR"
}
]
}
],
"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()."
}
],
"metrics": [
{
"cvssV3_1": {
"baseScore": 7.8,
"baseSeverity": "HIGH",
"vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"version": "3.1"
}
}
],
"providerMetadata": {
"dateUpdated": "2026-06-28T06:37:01.760Z",
"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"shortName": "Linux"
},
"references": [
{
"url": "https://git.kernel.org/stable/c/8dbed691e43a50903658130bde0fcb5abc425b37"
},
{
"url": "https://git.kernel.org/stable/c/9b40bdc2a3298225dffab8158208a0d8c6300578"
},
{
"url": "https://git.kernel.org/stable/c/fd470f0a97b8e9a125f520265d2f3b088ffb5b8a"
},
{
"url": "https://git.kernel.org/stable/c/ceafb893b12f23331dcc5ff9587e643c3a40ee9f"
},
{
"url": "https://git.kernel.org/stable/c/2e0e74c59b2761a414d9f48d7bee1e45220b2427"
},
{
"url": "https://git.kernel.org/stable/c/96a4713ae041cc85e712bac682cd2e644004d6c6"
},
{
"url": "https://git.kernel.org/stable/c/474d6c771d798bca84f0a140b611e36743511e18"
},
{
"url": "https://git.kernel.org/stable/c/98d0912e9f841e5529a5b89a972805f34cb1c69d"
}
],
"title": "net: skbuff: fix missing zerocopy reference in pskb_carve helpers",
"x_generator": {
"engine": "bippy-1.2.0"
}
}
},
"cveMetadata": {
"assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"assignerShortName": "Linux",
"cveId": "CVE-2026-52943",
"datePublished": "2026-06-24T09:00:12.292Z",
"dateReserved": "2026-06-09T07:44:35.371Z",
"dateUpdated": "2026-06-30T12:09:45.796Z",
"state": "PUBLISHED"
},
"dataType": "CVE_RECORD",
"dataVersion": "5.2"
}
Loading…
Loading…
Sightings
| Author | Source | Type | Date |
|---|
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.
Loading…
Loading…