CVE-2026-98959
Full vulnerability record from the local CVENow database.
Description
In the Linux kernel, the following vulnerability has been resolved: btrfs: fix xattr replace when multiple xattrs are packed in the same item If we have a btrfs_dir_item item that packs multiple xattrs and then we replace the value of one of them (with the setxattr(2) family of syscalls) with another value of a different size, we end up not having a fully initialized btrfs_dir_item, resulting in a corruption that the tree checker will detect at extent buffer writeback time. This is because in btrfs_setxattr() when we find a btrfs_dir_item with multiple xattrs (due to the crc32c hash of their name being the same) we delete one of the xattr items (btrfs_dir_item) and then insert a new one, but the deletion and insertion results in shifting existing data in the leaf and therefore when the new value of a xattr has a different size, the new btrfs_dir_item is placed in a leaf section that was not initialized and we only copy the value's data and set the value's length in the new btrfs_dir_item, without setting the name, the name's length, the key (which must be all zeroes for xattrs), flags (BTRFS_FT_XATTR) and transaction ID. The following script reproduces the issue: $ cat test.sh #!/bin/bash DEV=/dev/sdi MNT=/mnt/sdi mkfs.btrfs -f $DEV mount $DEV $MNT touch $MNT/testfile # Add two xattrs that, on btrfs, have the same hash (crc32c) for their # name and therefore are packed into the same btrfs_dir_item. setfattr -n user.foobar -v 123 $MNT/testfile setfattr -n user.WvG1c1Td -v qwerty $MNT/testfile # Verify the xattrs are present. echo "xattrs before:" getfattr --absolute-names --dump $MNT/testfile # Now replace the value of the foobar xattr with a significantly larger # value. setfattr -n user.foobar -v abcdefghijklmnopqrstuvwxyz $MNT/testfile # Check the xattrs have the expected values. echo "xattrs after:" getfattr --absolute-names --dump $MNT/testfile umount $MNT Running it: $ ./test.sh (...) xattrs before: # file: /mnt/sdi/testfile user.WvG1c1Td="qwerty" user.foobar="123" xattrs after: # file: /mnt/sdi/testfile user.WvG1c1Td="qwerty" So the "user.foobar" xattr is missing and there was a transaction abort when unmounting the fs with the following traces in dmesg: $ dmesg [869800.159271] BTRFS warning (device sdi): access to eb bytenr 30474240 len 16384 out of range start 16015 len 25964 [869800.159293] ------------[ cut here ]------------ [869800.159296] WARNING: fs/btrfs/extent_io.c:4408 at report_eb_range+0x44/0x60 [btrfs], CPU#8: getfattr/2605179 [869800.168961] Modules linked in: btrfs dm_thin_pool (...) [869800.190527] CPU: 8 UID: 0 PID: 2605179 Comm: getfattr Tainted: G W 7.3.0-rc3-btrfs-next-244+ #1 PREEMPT(full) [869800.193726] Tainted: [W]=WARN [869800.194502] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014 [869800.197576] RIP: 0010:report_eb_range+0x44/0x60 [btrfs] [869800.198985] Code: 48 8b 7b 18 (...) [869800.203531] RSP: 0018:ffffce4541937d58 EFLAGS: 00010246 [869800.204609] RAX: 0000000000000000 RBX: ffff8dde054b8738 RCX: 0000000000000000 [869800.206137] RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffffc04c92a0 [869800.207645] RBP: 0000000000003e8f R08: 0000000000000000 R09: 3fffffffffefffff [869800.226175] R10: ffffce4541937a88 R11: 0000000000000003 R12: 000000000000656c [869800.227594] R13: ffff8dde14be800f R14: 000000000000656c R15: 0000000000000069 [869800.229097] FS: 00007f59023bb780(0000) GS:ffff8de5788ed000(0000) knlGS:0000000000000000 [869800.231137] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [869800.232321] CR2: 0000558dc45e6a78 CR3: 0000000765b16004 CR4: 0000000000370ef0 [869800.233783] Call Trace: [869800.234330] <TASK> [869800.234791] read_extent_buffer+0x4d/0x100 [btrfs] [869800.235898] btrfs_listxattr+0x199/0x240 [btrfs] [869800.236912] vfs_listxattr+0x51/0 ---truncated---
View original CVE JSON
{
"id": "CVE-2026-98959",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"published": "2026-10-23T13:17:17.233",
"lastModified": "2026-10-24T14:16:49.307",
"vulnStatus": "Received",
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix xattr replace when multiple xattrs are packed in the same item\n\nIf we have a btrfs_dir_item item that packs multiple xattrs and then we\nreplace the value of one of them (with the setxattr(2) family of syscalls)\nwith another value of a different size, we end up not having a fully\ninitialized btrfs_dir_item, resulting in a corruption that the tree\nchecker will detect at extent buffer writeback time.\n\nThis is because in btrfs_setxattr() when we find a btrfs_dir_item with\nmultiple xattrs (due to the crc32c hash of their name being the same)\nwe delete one of the xattr items (btrfs_dir_item) and then insert a new\none, but the deletion and insertion results in shifting existing data in\nthe leaf and therefore when the new value of a xattr has a different size,\nthe new btrfs_dir_item is placed in a leaf section that was not\ninitialized and we only copy the value's data and set the value's length\nin the new btrfs_dir_item, without setting the name, the name's length,\nthe key (which must be all zeroes for xattrs), flags (BTRFS_FT_XATTR) and\ntransaction ID.\n\nThe following script reproduces the issue:\n\n $ cat test.sh\n #!/bin/bash\n\n DEV=/dev/sdi\n MNT=/mnt/sdi\n\n mkfs.btrfs -f $DEV\n mount $DEV $MNT\n\n touch $MNT/testfile\n\n # Add two xattrs that, on btrfs, have the same hash (crc32c) for their\n # name and therefore are packed into the same btrfs_dir_item.\n setfattr -n user.foobar -v 123 $MNT/testfile\n setfattr -n user.WvG1c1Td -v qwerty $MNT/testfile\n\n # Verify the xattrs are present.\n echo \"xattrs before:\"\n getfattr --absolute-names --dump $MNT/testfile\n\n # Now replace the value of the foobar xattr with a significantly larger\n # value.\n setfattr -n user.foobar -v abcdefghijklmnopqrstuvwxyz $MNT/testfile\n\n # Check the xattrs have the expected values.\n echo \"xattrs after:\"\n getfattr --absolute-names --dump $MNT/testfile\n\n umount $MNT\n\nRunning it:\n\n $ ./test.sh\n (...)\n xattrs before:\n # file: /mnt/sdi/testfile\n user.WvG1c1Td=\"qwerty\"\n user.foobar=\"123\"\n\n xattrs after:\n # file: /mnt/sdi/testfile\n user.WvG1c1Td=\"qwerty\"\n\nSo the \"user.foobar\" xattr is missing and there was a transaction abort\nwhen unmounting the fs with the following traces in dmesg:\n\n $ dmesg\n [869800.159271] BTRFS warning (device sdi): access to eb bytenr 30474240 len 16384 out of range start 16015 len 25964\n [869800.159293] ------------[ cut here ]------------\n [869800.159296] WARNING: fs/btrfs/extent_io.c:4408 at report_eb_range+0x44/0x60 [btrfs], CPU#8: getfattr/2605179\n [869800.168961] Modules linked in: btrfs dm_thin_pool (...)\n [869800.190527] CPU: 8 UID: 0 PID: 2605179 Comm: getfattr Tainted: G W 7.3.0-rc3-btrfs-next-244+ #1 PREEMPT(full)\n [869800.193726] Tainted: [W]=WARN\n [869800.194502] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.2-0-gea1b7a073390-prebuilt.qemu.org 04/01/2014\n [869800.197576] RIP: 0010:report_eb_range+0x44/0x60 [btrfs]\n [869800.198985] Code: 48 8b 7b 18 (...)\n [869800.203531] RSP: 0018:ffffce4541937d58 EFLAGS: 00010246\n [869800.204609] RAX: 0000000000000000 RBX: ffff8dde054b8738 RCX: 0000000000000000\n [869800.206137] RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffffc04c92a0\n [869800.207645] RBP: 0000000000003e8f R08: 0000000000000000 R09: 3fffffffffefffff\n [869800.226175] R10: ffffce4541937a88 R11: 0000000000000003 R12: 000000000000656c\n [869800.227594] R13: ffff8dde14be800f R14: 000000000000656c R15: 0000000000000069\n [869800.229097] FS: 00007f59023bb780(0000) GS:ffff8de5788ed000(0000) knlGS:0000000000000000\n [869800.231137] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n [869800.232321] CR2: 0000558dc45e6a78 CR3: 0000000765b16004 CR4: 0000000000370ef0\n [869800.233783] Call Trace:\n [869800.234330] <TASK>\n [869800.234791] read_extent_buffer+0x4d/0x100 [btrfs]\n [869800.235898] btrfs_listxattr+0x199/0x240 [btrfs]\n [869800.236912] vfs_listxattr+0x51/0\n---truncated---"
}
],
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "unaffected",
"programFiles": [
"fs/btrfs/xattr.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "5f5bc6b1e2d5a6f827bc860ef2dc5b6f365d1339",
"lessThan": "7a53bb4668b319fc6c8a3ce2c21635125c7d2712",
"versionType": "git",
"status": "affected"
},
{
"version": "5f5bc6b1e2d5a6f827bc860ef2dc5b6f365d1339",
"lessThan": "5877d7138cc4359d26fd7b010eedfd1b3162348f",
"versionType": "git",
"status": "affected"
},
{
"version": "5f5bc6b1e2d5a6f827bc860ef2dc5b6f365d1339",
"lessThan": "a97114b9b00ed3d05156f3b2ddbf797296260389",
"versionType": "git",
"status": "affected"
},
{
"version": "5f5bc6b1e2d5a6f827bc860ef2dc5b6f365d1339",
"lessThan": "c1803697a60f22743aa28ad522f805e92d45e3f0",
"versionType": "git",
"status": "affected"
},
{
"version": "5f5bc6b1e2d5a6f827bc860ef2dc5b6f365d1339",
"lessThan": "858bee1c77857aabcc2327cd32dd8266332de332",
"versionType": "git",
"status": "affected"
},
{
"version": "43f2e3615d181a7028ab797114c5960977669b2a",
"versionType": "git",
"status": "affected"
},
{
"version": "a873146ce4fb025c0b5c1322af5a6bad042f5363",
"versionType": "git",
"status": "affected"
},
{
"version": "02590fd855d1690568b2fa439c942e933221b57a",
"versionType": "git",
"status": "affected"
},
{
"version": "55e97f654cbbbef70f9714f0e113604dd931e360",
"versionType": "git",
"status": "affected"
},
{
"version": "3.10.83",
"lessThan": "3.11",
"versionType": "semver",
"status": "affected"
},
{
"version": "3.12.45",
"lessThan": "3.13",
"versionType": "semver",
"status": "affected"
},
{
"version": "3.14.47",
"lessThan": "3.15",
"versionType": "semver",
"status": "affected"
},
{
"version": "3.18.19",
"lessThan": "3.19",
"versionType": "semver",
"status": "affected"
}
]
},
{
"vendor": "Linux",
"product": "Linux",
"defaultStatus": "affected",
"programFiles": [
"fs/btrfs/xattr.c"
],
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"versions": [
{
"version": "3.19",
"status": "affected"
},
{
"version": "0",
"lessThan": "3.19",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.6.160",
"lessThanOrEqual": "6.6.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.12.113",
"lessThanOrEqual": "6.12.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "6.18.57",
"lessThanOrEqual": "6.18.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.2.11",
"lessThanOrEqual": "7.2.*",
"versionType": "semver",
"status": "unaffected"
},
{
"version": "7.3",
"lessThanOrEqual": "*",
"versionType": "original_commit_for_fix",
"status": "unaffected"
}
]
}
]
}
],
"metrics": {
"cvssMetricV31": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"type": "Secondary",
"cvssData": {
"version": "3.1",
"vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
"baseScore": 9.8,
"baseSeverity": "CRITICAL",
"attackVector": "NETWORK",
"attackComplexity": "LOW",
"privilegesRequired": "NONE",
"userInteraction": "NONE",
"scope": "UNCHANGED",
"confidentialityImpact": "HIGH",
"integrityImpact": "HIGH",
"availabilityImpact": "HIGH"
},
"exploitabilityScore": 3.9,
"impactScore": 5.9
}
]
},
"references": [
{
"url": "https://git.kernel.org/stable/c/5877d7138cc4359d26fd7b010eedfd1b3162348f",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/7a53bb4668b319fc6c8a3ce2c21635125c7d2712",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/858bee1c77857aabcc2327cd32dd8266332de332",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/a97114b9b00ed3d05156f3b2ddbf797296260389",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/c1803697a60f22743aa28ad522f805e92d45e3f0",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
]
}