cbcvebase.
CVE-2026-43503
published 2026-05-23

CVE-2026-43503: In the Linux kernel, the following vulnerability has been resolved: net: skbuff: propagate shared-frag marker through frag-transfer helpers Two frag-transfer…

PriorityP348high8.8CVSS 3.1
AVLACLPRLUINSCCHIHAH
EPSS
0.34%
26.2th percentile
In the Linux kernel, the following vulnerability has been resolved: net: skbuff: propagate shared-frag marker through frag-transfer helpers Two frag-transfer helpers (__pskb_copy_fclone() and skb_shift()) fail to propagate the SKBFL_SHARED_FRAG bit in skb_shinfo()->flags when moving frags from source to destination. __pskb_copy_fclone() defers the rest of the shinfo metadata to skb_copy_header() after copying frag descriptors, but that helper only carries over gso_{size,segs, type} and never touches skb_shinfo()->flags; skb_shift() moves frag descriptors directly and leaves flags untouched. As a result, the destination skb keeps a reference to the same externally-owned or page-cache-backed pages while reporting skb_has_shared_frag() as false. The mismatch is harmful in any in-place writer that uses skb_has_shared_frag() to decide whether shared pages must be detoured through skb_cow_data(). ESP input is one such writer (esp4.c, esp6.c), and a single nft 'dup to ' rule -- or any other nf_dup_ipv4() / xt_TEE caller -- is enough to land a pskb_copy()'d skb in esp_input() with the marker stripped, letting an unprivileged user write into the page cache of a root-owned read-only file via authencesn-ESN stray writes. Set SKBFL_SHARED_FRAG on the destination whenever frag descriptors were actually moved from the source. skb_copy() and skb_copy_expand() share skb_copy_header() too but linearize all paged data into freshly allocated head storage and emerge with nr_frags == 0, so skb_has_shared_frag() returns false on its own; they need no change. The same omission exists in skb_gro_receive() and skb_gro_receive_list(). The former moves the incoming skb's frag descriptors into the accumulator's last sub-skb via two paths (a direct frag-move loop and the head_frag + memcpy path); the latter chains the incoming skb whole onto p's frag_list. Downstream skb_segment() reads only skb_shinfo(p)->flags, and skb_segment_list() reuses each sub-skb's shinfo as the nskb -- both p and

Affected

83 ranges· showing 25
VendorProductVersion rangeFixed in
linuxlinux
linuxlinux>= cef401de7be8c4e155c6746bfccf721a4fa5fab9 < fbeab9555564a1b98e8582cd106dfe46c4606991fbeab9555564a1b98e8582cd106dfe46c4606991
linuxlinux>= cef401de7be8c4e155c6746bfccf721a4fa5fab9 < 179f1852bdedc300e373e807cc102cd81feff196179f1852bdedc300e373e807cc102cd81feff196
linuxlinux>= cef401de7be8c4e155c6746bfccf721a4fa5fab9 < 12401fcfb01f53ccc63ab0a3246570fe8f3105ee12401fcfb01f53ccc63ab0a3246570fe8f3105ee
linuxlinux>= cef401de7be8c4e155c6746bfccf721a4fa5fab9 < 989214c66884d70716d83dc1d0bf5e16287bf349989214c66884d70716d83dc1d0bf5e16287bf349
linuxlinux>= cef401de7be8c4e155c6746bfccf721a4fa5fab9 < fc6eb39c55e97df2f94ad974b8a5bbcd019da2c8fc6eb39c55e97df2f94ad974b8a5bbcd019da2c8
linuxlinux>= cef401de7be8c4e155c6746bfccf721a4fa5fab9 < ff375cc75f9167168db38e0464a482d5fbc8d81dff375cc75f9167168db38e0464a482d5fbc8d81d
linuxlinux>= cef401de7be8c4e155c6746bfccf721a4fa5fab9 < 9bc9d6d6967a2239aa57af2aa53554eddd640d209bc9d6d6967a2239aa57af2aa53554eddd640d20
linuxlinux>= cef401de7be8c4e155c6746bfccf721a4fa5fab9 < 48f6a5356a33dd78e7144ae1faef95ffc990aae048f6a5356a33dd78e7144ae1faef95ffc990aae0
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel
linuxlinux_kernel>= 3.9 < 5.10.2575.10.257
linuxlinux_kernel>= 5.11 < 5.15.2085.15.208
linuxlinux_kernel>= 5.16 < 6.1.1746.1.174
linuxlinux_kernel>= 6.13 < 6.18.336.18.33
linuxlinux_kernel>= 6.19 < 7.0.107.0.10
linuxlinux_kernel>= 6.2 < 6.6.1416.6.141
linuxlinux_kernel>= 6.7 < 6.12.916.12.91
ubuntulinux
ubuntulinux-aws
ubuntulinux-aws-5.15
ubuntulinux-aws-5.4

CVSS provenance

nvdv3.18.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
vendor_ubuntu8.8HIGH
vendor_redhat7.0HIGH
Stop checking back — get the weekly exploitation signal.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.