{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-43503", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-05-01T14:12:56.014Z", "datePublished": "2026-05-23T11:44:01.103Z", "dateUpdated": "2026-05-23T13:20:26.042Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-05-23T13:20:26.042Z"}, "descriptions": [{"lang": "en", "value": "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_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."}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/core/gro.c", "net/core/skbuff.c", "net/ipv4/tcp_output.c"], "versions": [{"version": "cef401de7be8c4e155c6746bfccf721a4fa5fab9", "lessThan": "fbeab9555564a1b98e8582cd106dfe46c4606991", "status": "affected", "versionType": "git"}, {"version": "cef401de7be8c4e155c6746bfccf721a4fa5fab9", "lessThan": "179f1852bdedc300e373e807cc102cd81feff196", "status": "affected", "versionType": "git"}, {"version": "cef401de7be8c4e155c6746bfccf721a4fa5fab9", "lessThan": "12401fcfb01f53ccc63ab0a3246570fe8f3105ee", "status": "affected", "versionType": "git"}, {"version": "cef401de7be8c4e155c6746bfccf721a4fa5fab9", "lessThan": "989214c66884d70716d83dc1d0bf5e16287bf349", "status": "affected", "versionType": "git"}, {"version": "cef401de7be8c4e155c6746bfccf721a4fa5fab9", "lessThan": "fc6eb39c55e97df2f94ad974b8a5bbcd019da2c8", "status": "affected", "versionType": "git"}, {"version": "cef401de7be8c4e155c6746bfccf721a4fa5fab9", "lessThan": "ff375cc75f9167168db38e0464a482d5fbc8d81d", "status": "affected", "versionType": "git"}, {"version": "cef401de7be8c4e155c6746bfccf721a4fa5fab9", "lessThan": "9bc9d6d6967a2239aa57af2aa53554eddd640d20", "status": "affected", "versionType": "git"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/core/gro.c", "net/core/skbuff.c", "net/ipv4/tcp_output.c"], "versions": [{"version": "3.9", "status": "affected"}, {"version": "0", "lessThan": "3.9", "status": "unaffected", "versionType": "semver"}, {"version": "5.10.257", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver"}, {"version": "5.15.208", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.1.174", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.6.141", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.12.91", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver"}, {"version": "6.18.33", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.0.10", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver"}]}], "cpeApplicability": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.9", "versionEndExcluding": "5.10.257"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.9", "versionEndExcluding": "5.15.208"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.9", "versionEndExcluding": "6.1.174"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.9", "versionEndExcluding": "6.6.141"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.9", "versionEndExcluding": "6.12.91"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.9", "versionEndExcluding": "6.18.33"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.9", "versionEndExcluding": "7.0.10"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/fbeab9555564a1b98e8582cd106dfe46c4606991"}, {"url": "https://git.kernel.org/stable/c/179f1852bdedc300e373e807cc102cd81feff196"}, {"url": "https://git.kernel.org/stable/c/12401fcfb01f53ccc63ab0a3246570fe8f3105ee"}, {"url": "https://git.kernel.org/stable/c/989214c66884d70716d83dc1d0bf5e16287bf349"}, {"url": "https://git.kernel.org/stable/c/fc6eb39c55e97df2f94ad974b8a5bbcd019da2c8"}, {"url": "https://git.kernel.org/stable/c/ff375cc75f9167168db38e0464a482d5fbc8d81d"}, {"url": "https://git.kernel.org/stable/c/9bc9d6d6967a2239aa57af2aa53554eddd640d20"}], "title": "net: skbuff: propagate shared-frag marker through frag-transfer helpers", "x_generator": {"engine": "bippy-1.2.0"}}}}