High 7.8Published Jun 24, 2026

CVE-2026-52943net: skbuff: fix missing zerocopy reference in pskb_carve helpers

Updated under an hour ago (Oct 27, 2026, 8:10 PM ET)

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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().

CVSS: 7.8 HIGH (v3.1, CNA)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Weakness (CWE): CWE-911, CWE-416
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Modified
Record last updated: Oct 19, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from 6fa01ccd883021105e9f8af7d04b9f156fa3494a before 8dbed691e43a50903658130bde0fcb5abc425b37; from 6fa01ccd883021105e9f8af7d04b9f156fa3494a before 9b40bdc2a3298225dffab8158208a0d8c6300578; from 6fa01ccd883021105e9f8af7d04b9f156fa3494a before fd470f0a97b8e9a125f520265d2f3b088ffb5b8a; from 6fa01ccd883021105e9f8af7d04b9f156fa3494a before ceafb893b12f23331dcc5ff9587e643c3a40ee9f; 6fa01ccd883021105e9f8af7d04b9f156fa3494a builds before 2e0e74c59b2761a414d9f48d7bee1e45220b2427; from 6fa01ccd883021105e9f8af7d04b9f156fa3494a before 96a4713ae041cc85e712bac682cd2e644004d6c6; from 6fa01ccd883021105e9f8af7d04b9f156fa3494a before 474d6c771d798bca84f0a140b611e36743511e18; from 6fa01ccd883021105e9f8af7d04b9f156fa3494a before 98d0912e9f841e5529a5b89a972805f34cb1c69d	CNA record
Red Hat Red Hat Enterprise Linux 10 redhat:enterprise_linux	10	CISA ADP
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem siemens:simatic_s7_1500_tm_mfp_gnu_linux_subsystem (from the name)	all versions	CISA ADP
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
linux linux_kernel linux:linux_kernel	from 4.7 before 5.10.259; from 5.11 before 5.15.210; from 5.16 before 6.1.176; from 6.2 before 6.6.143; from 6.7 before 6.12.93; from 6.13 before 6.18.35; from 6.19 before 7.0.12; 7.1; and 4 more ranges	NVD

References

References

https://git.kernel.org/stable/c/8dbed691e43a50903658130bde0fcb5abc425b37	patch
https://git.kernel.org/stable/c/9b40bdc2a3298225dffab8158208a0d8c6300578	patch
https://git.kernel.org/stable/c/fd470f0a97b8e9a125f520265d2f3b088ffb5b8a	patch
https://git.kernel.org/stable/c/ceafb893b12f23331dcc5ff9587e643c3a40ee9f	patch
https://git.kernel.org/stable/c/2e0e74c59b2761a414d9f48d7bee1e45220b2427	patch
https://git.kernel.org/stable/c/96a4713ae041cc85e712bac682cd2e644004d6c6	patch
https://git.kernel.org/stable/c/474d6c771d798bca84f0a140b611e36743511e18	patch
https://git.kernel.org/stable/c/98d0912e9f841e5529a5b89a972805f34cb1c69d	patch
https://access.redhat.com/security/cve/CVE-2026-52943	third-party-advisory
https://bugzilla.redhat.com/show_bug.cgi?id=2492137	third-party-advisory
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The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.