{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-89649","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-09-11T19:38:34.742Z","datePublished":"2026-09-11T19:45:40.118Z","dateUpdated":"2026-09-14T12:01:44.932Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-09-14T12:01:44.932Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nceph: bound xattr value length in __build_xattrs()\n\n__build_xattrs() decodes the MDS-supplied xattr blob one attribute at a\ntime. For each attribute it reads a 32-bit name length, advances past the\nname bytes, reads a 32-bit value length, records the value pointer, and\nadvances past the value bytes. The two length fields are read with\nceph_decode_32_safe(), but the value bytes themselves are advanced over\nwith a bare \"p += len\" and no ceph_decode_need() check that \"len\" bytes\nremain in the blob.\n\nFor every attribute except the last, the next iteration's\nceph_decode_32_safe() on the following name length implicitly verifies\nthat the previous value did not run past the blob end. The final\nattribute has no successor, so its decoded value length is never checked\nagainst the blob bounds. A malicious or compromised metadata server can\nset the last attribute's value length larger than the bytes actually\npresent in the blob.\n\nThe blob is a dedicated kvmalloc() allocation sized to the wire length\n(ceph_buffer_new() in ceph_fill_inode()). __set_xattr() records the\noversized length in xattr->val_len verbatim, and a later getxattr(2) runs\nmemcpy(value, xattr->val, xattr->val_len) into a user-supplied buffer,\ncopying bytes past the end of the allocation back to user space.\n\nImpact: a malicious metadata server discloses adjacent kernel heap bytes\nto a local user via getxattr(2) on a CephFS file. Add the missing\nceph_decode_need() so an out-of-bounds value length on the final\nattribute fails the decode and returns -EIO instead of being stored."}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","baseScore":9.1,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - The MDS-supplied xattr blob is delivered over the kernel Ceph messenger TCP session in inode replies (parse_reply_info_in → ceph_fill_inode) and CEPH_MSG_CLIENT_CAPS (handle_cap_grant), so a malicious or compromised MDS reaches __build_xattrs() with network protocol data.\nAC:L - The attacker fully controls the last attribute's 32-bit value length in the xattr blob; setting it larger than the remaining kvmalloc'd wire bytes reliably records an oversized val_len with no race, special memory layout, or rare kernel config.\nPR:N - Exploitation requires only the ability to send crafted MDS replies or cap grants as the remote cluster peer on an established session; no local account, capability, or user-namespace privilege on the victim host is needed.\nUI:N - Once CephFS is mounted, MDS replies and cap grants are processed automatically, and ceph_get_acl()/__ceph_getxattr() run on ordinary inode permission checks and xattr queries without a further victim mount or click at exploit time.\nS:U - The out-of-bounds heap read, userspace disclosure, and possible oops remain inside the client kernel's own security authority and do not cross a VM, IOMMU, or other distinct trust boundary.\nC:H - __set_xattr() stores the oversized length and getxattr memcpy()s that many bytes from the undersized blob into a user buffer (up to XATTR_SIZE_MAX), disclosing adjacent kernel heap including pointers; the in-kernel ACL path can copy still larger extents.\nI:N - The bug is an out-of-bounds read into a destination buffer sized from the claimed length (VFS kvzalloc or ceph_get_acl kzalloc); it does not provide an attacker-selected write into kernel memory.\nA:H - An oversized value length that extends into unmapped kernel addresses faults the in-kernel memcpy in __ceph_getxattr() or ceph_get_acl(), causing a kernel oops or panic the MDS can trigger repeatedly."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ceph/xattr.c"],"versions":[{"version":"355da1eb7a1f91c276b991764e951bbcd8047599","lessThan":"848b80ca6b410f350d08b8ac19a00ef88223f2ea","status":"affected","versionType":"git"},{"version":"355da1eb7a1f91c276b991764e951bbcd8047599","lessThan":"01e3f19c301d492e12f16b3b463ac14d7cf3ebe7","status":"affected","versionType":"git"},{"version":"355da1eb7a1f91c276b991764e951bbcd8047599","lessThan":"cb0cd79ae80476d1bc06bd9678484b6736f19588","status":"affected","versionType":"git"},{"version":"355da1eb7a1f91c276b991764e951bbcd8047599","lessThan":"61f085cb8976c9cebc90e1a8933e4cc1ad8b0fce","status":"affected","versionType":"git"},{"version":"355da1eb7a1f91c276b991764e951bbcd8047599","lessThan":"38be2f3c41ecaba58bb92dc16603e09ba9fd64f1","status":"affected","versionType":"git"},{"version":"355da1eb7a1f91c276b991764e951bbcd8047599","lessThan":"1dd356310b1660215f9a3626580bf8b363ef981e","status":"affected","versionType":"git"},{"version":"355da1eb7a1f91c276b991764e951bbcd8047599","lessThan":"b12b3320c81fd72ab36388fb2445fec9c3038f10","status":"affected","versionType":"git"},{"version":"355da1eb7a1f91c276b991764e951bbcd8047599","lessThan":"68d541754d6cd3bb98d1fd8314f57e5eb533557d","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["fs/ceph/xattr.c"],"versions":[{"version":"2.6.34","status":"affected"},{"version":"0","lessThan":"2.6.34","status":"unaffected","versionType":"semver"},{"version":"5.10.270","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.221","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.188","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.157","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.109","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.50","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"7.2.4","lessThanOrEqual":"7.2.*","status":"unaffected","versionType":"semver"},{"version":"7.3-rc1","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.34","versionEndExcluding":"5.10.270"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.34","versionEndExcluding":"5.15.221"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.34","versionEndExcluding":"6.1.188"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.34","versionEndExcluding":"6.6.157"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.34","versionEndExcluding":"6.12.109"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.34","versionEndExcluding":"6.18.50"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.34","versionEndExcluding":"7.2.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.34","versionEndExcluding":"7.3-rc1"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/848b80ca6b410f350d08b8ac19a00ef88223f2ea"},{"url":"https://git.kernel.org/stable/c/01e3f19c301d492e12f16b3b463ac14d7cf3ebe7"},{"url":"https://git.kernel.org/stable/c/cb0cd79ae80476d1bc06bd9678484b6736f19588"},{"url":"https://git.kernel.org/stable/c/61f085cb8976c9cebc90e1a8933e4cc1ad8b0fce"},{"url":"https://git.kernel.org/stable/c/38be2f3c41ecaba58bb92dc16603e09ba9fd64f1"},{"url":"https://git.kernel.org/stable/c/1dd356310b1660215f9a3626580bf8b363ef981e"},{"url":"https://git.kernel.org/stable/c/b12b3320c81fd72ab36388fb2445fec9c3038f10"},{"url":"https://git.kernel.org/stable/c/68d541754d6cd3bb98d1fd8314f57e5eb533557d"}],"title":"ceph: bound xattr value length in __build_xattrs()","x_generator":{"engine":"bippy-1.2.0"}}}}