CVE-2026-52943 — net: skbuff: fix missing zerocopy reference in pskb_carve helpers
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().
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.2% (30-day exploitation probability)+2
- Technical severity (high)+6
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
- Documented patch — git.kernel.org (NIST National Vulnerability Database)
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Linux Linux, Linux Linux Kernel).
- Apply the fixed version or the patch documented under Remediation.
- Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Linux | Linux |
version 4.7≥ 6fa01ccd883021105e9f8af7d04b9f156fa3494a and < 98d0912e9f841e5529a5b89a972805f34cb1c69d≥ 6fa01ccd883021105e9f8af7d04b9f156fa3494a and < 474d6c771d798bca84f0a140b611e36743511e18≥ 6fa01ccd883021105e9f8af7d04b9f156fa3494a and < 96a4713ae041cc85e712bac682cd2e644004d6c6≥ 6fa01ccd883021105e9f8af7d04b9f156fa3494a and < 2e0e74c59b2761a414d9f48d7bee1e45220b2427≥ 6fa01ccd883021105e9f8af7d04b9f156fa3494a and < ceafb893b12f23331dcc5ff9587e643c3a40ee9f≥ 6fa01ccd883021105e9f8af7d04b9f156fa3494a and < fd470f0a97b8e9a125f520265d2f3b088ffb5b8a≥ 6fa01ccd883021105e9f8af7d04b9f156fa3494a and < 9b40bdc2a3298225dffab8158208a0d8c6300578 and 1 more≥ 6fa01ccd883021105e9f8af7d04b9f156fa3494a and < 8dbed691e43a50903658130bde0fcb5abc425b37 |
Vulnerable | CVE Program (cve.org) e CISA ADP |
| Linux | Linux Kernel |
version 7.1-rc4version 7.1-rc5≥ 4.7 and < 5.10.259version 7.1-rc3version 7.1-rc2version 7.1-rc1≥ 6.19 and < 7.0.12≥ 6.13 and < 6.18.35 and 4 more≥ 6.7 and < 6.12.93≥ 6.2 and < 6.6.143≥ 5.16 and < 6.1.176≥ 5.11 and < 5.15.210 |
Vulnerable | NIST National Vulnerability Database |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 7.8 | CVSS 3.1 | High | 1.8 | 5.9 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database |
| 7.8 | CVSS 3.1 | High | 1.8 | 5.9 | 0b0ca135-0b70-47e7-9f44-1890c2a1c46c via NIST National Vulnerability Database |
| 7.8 | CVSS 3.1 | High | — | — | GitHub, Inc. via GitHub Security Advisories |
| 7.8 | CVSS 3.1 | High | — | — | Linux via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (score shown at the top: 416baaa9-dc9f-4396-8d5f-8c081fb06d67) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.24%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
- Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · linux/linux
- Record published
- Fix documented
- CVSS changed · 7.8
- Source status changed · → Modified
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 2× References added · Oct 14, 2026 – Oct 15, 2026
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
16 on the record
- git.kernel.org/stable/c/474d6c771d798bca84f0a140b611e36743511e18
- git.kernel.org/stable/c/96a4713ae041cc85e712bac682cd2e644004d6c6
- git.kernel.org/stable/c/2e0e74c59b2761a414d9f48d7bee1e45220b2427
- git.kernel.org/stable/c/ceafb893b12f23331dcc5ff9587e643c3a40ee9f
- git.kernel.org/stable/c/8dbed691e43a50903658130bde0fcb5abc425b37
- git.kernel.org/stable/c/98d0912e9f841e5529a5b89a972805f34cb1c69d
- git.kernel.org/stable/c/fd470f0a97b8e9a125f520265d2f3b088ffb5b8a
- git.kernel.org/stable/c/9b40bdc2a3298225dffab8158208a0d8c6300578
- nvd.nist.gov/vuln/detail/CVE-2026-52943
- cert-portal.siemens.com/productcert/html/ssa-457936.html
- cert-portal.siemens.com/productcert/html/ssa-019113.html
- github.com/advisories/GHSA-vwrr-994w-h832
- cert-portal.siemens.com/productcert/html/ssa-784472.html
- bugzilla.redhat.com/show_bug.cgi
- access.redhat.com/security/cve/CVE-2026-52943
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-52943.json
Elsewhere on this site
Related CVEs (same products)
- Critical CVE-2026-99999 ipv4: validate checksum_start before completing checksum 10h
- Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 10h
- Unknown CVE-2026-98431 RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency 1d
- Unknown CVE-2026-98430 RDMA/efa: Keep admin queues alive while IRQ is registered 1d
- Unknown CVE-2026-98429 RDMA/efa: Keep EQ resources alive while IRQ is registered 1d
- Unknown CVE-2026-98428 ALSA: usb: 6fire: Avoid embedded URBs 1d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No CISA SSVC assessment.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-52943 is "net: skbuff: fix missing zerocopy reference in pskb_carve helpers", rated High. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.8 describes technical severity. EPSS 0.24% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
Comments
Moderated technical discussion. Read the community guidelines.
No comments yet.
Sign in or create an account to comment and suggest corrections.