{"id":"CVE-2026-43503","title":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: skbuff: propagate shared-frag marker through frag-transfer helpers\n\nTwo frag-transfer helpers (__pskb_copy_fclone() and skb_shift()) fail\nto propagate the SKBFL_SH…","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: skbuff: propagate shared-frag marker through frag-transfer helpers\n\nTwo frag-transfer helpers (__pskb_copy_fclone() and skb_shift()) fail\nto propagate the SKBFL_SH…","severity":"high","cvss":8.8,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","cwe":["CWE-664"],"vendor":"linux","product":"linux_kernel","affected":["linux_kernel >= 3.9, < 5.10.257","linux_kernel >= 5.11, < 5.15.208","linux_kernel >= 5.16, < 6.1.174","linux_kernel >= 6.2, < 6.6.141","linux_kernel >= 6.7, < 6.12.91","linux_kernel >= 6.13, < 6.18.33","linux_kernel >= 6.19, < 7.0.10","linux_kernel = 7.1"],"patched":["linux_kernel 7.0.10"],"published":"2026-05-23","updated":"2026-07-02","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-43503","references":[{"url":"https://git.kernel.org/stable/c/12401fcfb01f53ccc63ab0a3246570fe8f3105ee","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/179f1852bdedc300e373e807cc102cd81feff196","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/48f6a5356a33dd78e7144ae1faef95ffc990aae0","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/989214c66884d70716d83dc1d0bf5e16287bf349","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9bc9d6d6967a2239aa57af2aa53554eddd640d20","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/fbeab9555564a1b98e8582cd106dfe46c4606991","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/fc6eb39c55e97df2f94ad974b8a5bbcd019da2c8","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ff375cc75f9167168db38e0464a482d5fbc8d81d","label":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://access.redhat.com/errata/RHSA-2026:19521","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:19540","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:19568","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:19569","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:19664","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:19666","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:19705","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:19711","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:19875","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:20051","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:20054","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:20087","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:20129","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:20130","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:20299","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:20593","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:21656","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:21690","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:21695","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:21702","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:23233","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:23240","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:23245","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:23468","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:23469","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:23470","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:23471","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:24814","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:25044","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/errata/RHSA-2026:33486","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://access.redhat.com/security/cve/CVE-2026-43503","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2480902","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43503.json","label":"0b0ca135-0b70-47e7-9f44-1890c2a1c46c"}],"tags":["nvd","exploit-available"],"epss":0.00337,"epssPercentile":0.27223,"ingestedAt":"2026-07-02T13:35:59.412Z","exploits":{"github":8,"githubRepos":["https://github.com/0xBlackash/CVE-2026-43503","https://github.com/entra1337/DirtyClone","https://github.com/mooder1/dirtyclone-CVE-2026-43503"],"checkedAt":"2026-09-23T07:14:05.090Z"},"exploitAvailable":true,"slug":"CVE-2026-43503","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nnet: skbuff: propagate shared-frag marker through frag-transfer helpers\n\nTwo frag-transfer helpers (__pskb_copy_fclone() and skb_shift()) fail\nto propagate the SKBFL_SHARED_FRAG bit in skb_shinfo()->flags when\nmoving frags from source to destination.  __pskb_copy_fclone() defers\nthe rest of the shinfo metadata to skb_copy_header() after copying\nfrag descriptors, but that helper only carries over gso_{size,segs,\ntype} and never touches skb_shinfo()->flags; skb_shift() moves frag\ndescriptors directly and leaves flags untouched.  As a result, the\ndestination skb keeps a reference to the same externally-owned or\npage-cache-backed pages while reporting skb_has_shared_frag() as\nfalse.\n\nThe mismatch is harmful in any in-place writer that uses\nskb_has_shared_frag() to decide whether shared pages must be detoured\nthrough skb_cow_data().  ESP input is one such writer (esp4.c,\nesp6.c), and a single nft 'dup to <local>' rule -- or any other\nnf_dup_ipv4() / xt_TEE caller -- is enough to land a pskb_copy()'d\nskb in esp_input() with the marker stripped, letting an unprivileged\nuser write into the page cache of a root-owned read-only file via\nauthencesn-ESN stray writes.\n\nSet SKBFL_SHARED_FRAG on the destination whenever frag descriptors\nwere actually moved from the source.  skb_copy() and skb_copy_expand()\nshare skb_copy_header() too but linearize all paged data into freshly\nallocated head storage and emerge with nr_frags == 0, so\nskb_has_shared_frag() returns false on its own; they need no change.\n\nThe same omission exists in skb_gro_receive() and skb_gro_receive_list().\nThe former moves the incoming skb's frag descriptors into the\naccumulator's last sub-skb via two paths (a direct frag-move loop and\nthe head_frag + memcpy path); the latter chains the incoming skb whole\nonto p's frag_list.  Downstream skb_segment() reads only\nskb_shinfo(p)->flags, and skb_segment_list() reuses each sub-skb's\nshinfo as the nskb -- both p and lp must carry the marker.\n\nThe same omission also exists in tcp_clone_payload(), which builds an\nMTU probe skb by moving frag descriptors from skbs on sk_write_queue\ninto a freshly allocated nskb.  The helper falls into the same family\nand warrants the same fix for consistency; no TCP TX-side in-place\nwriter is currently known to reach a user page through this gap, but\na future consumer depending on the marker would regress silently.\n\nThe same omission exists in skb_segment(): the per-iteration flag\nmerge takes only head_skb's flag, and the inner switch that rebinds\nfrag_skb to list_skb on head_skb-frags exhaustion does not fold the\nnew frag_skb's flag into nskb.  Fold frag_skb's flag at both sites\nso segments drawing frags from frag_list members carry the marker.\n\n## Affected\n\n- `linux_kernel >= 3.9, < 5.10.257`\n- `linux_kernel >= 5.11, < 5.15.208`\n- `linux_kernel >= 5.16, < 6.1.174`\n- `linux_kernel >= 6.2, < 6.6.141`\n- `linux_kernel >= 6.7, < 6.12.91`\n- `linux_kernel >= 6.13, < 6.18.33`\n- `linux_kernel >= 6.19, < 7.0.10`\n- `linux_kernel = 7.1`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `linux_kernel 7.0.10`","depth":"midnight","depthScore":60,"depthScoreParts":{"impact":48.4,"likelihood":0.1,"exploitation":12,"ransomware":0},"changes":[{"seq":5218,"id":"CVE-2026-43503","ts":1788887254028,"field":"exploit_available","old":"false","new":"true"},{"seq":4101,"id":"CVE-2026-43503","ts":1788886369880,"field":"exploit_available","old":"true","new":"false"},{"seq":2877,"id":"CVE-2026-43503","ts":1788883036216,"field":"exploit_available","old":"false","new":"true"},{"seq":1906,"id":"CVE-2026-43503","ts":1788882439297,"field":"exploit_available","old":"true","new":"false"},{"seq":998,"id":"CVE-2026-43503","ts":1788881873584,"field":"exploit_available","old":"false","new":"true"}]}