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CVE-2026-89649— ceph: bound xattr value length in __build_xattrs()

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于__build_xattrs()在解码MDS提供的xattr blob时未检查最后一个属性的值长度是否超出blob边界，导致恶意元数据服务器可设置过大的值长度，后续对CephFS文件的getxattr(2)调用可能将相邻内核堆内存字节复制到用户空间，造成信息泄露。

CVSS 9.1 · Critical EPSS 0.67% · P51

Affected Version Matrix 18

VendorProduct Version RangeStatus
Linux Linux 355da1eb7a1f91c276b991764e951bbcd8047599< 848b80ca6b410f350d08b8ac19a00ef88223f2ea affected
355da1eb7a1f91c276b991764e951bbcd8047599< 01e3f19c301d492e12f16b3b463ac14d7cf3ebe7 affected
355da1eb7a1f91c276b991764e951bbcd8047599< cb0cd79ae80476d1bc06bd9678484b6736f19588 affected
355da1eb7a1f91c276b991764e951bbcd8047599< 61f085cb8976c9cebc90e1a8933e4cc1ad8b0fce affected
355da1eb7a1f91c276b991764e951bbcd8047599< 38be2f3c41ecaba58bb92dc16603e09ba9fd64f1 affected
355da1eb7a1f91c276b991764e951bbcd8047599< 1dd356310b1660215f9a3626580bf8b363ef981e affected
355da1eb7a1f91c276b991764e951bbcd8047599< b12b3320c81fd72ab36388fb2445fec9c3038f10 affected
355da1eb7a1f91c276b991764e951bbcd8047599< 68d541754d6cd3bb98d1fd8314f57e5eb533557d affected
… +10 more rows
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I. Basic Information for CVE-2026-89649

Vulnerability Information
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Vulnerability Title
ceph: bound xattr value length in __build_xattrs()
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: ceph: bound xattr value length in __build_xattrs() __build_xattrs() decodes the MDS-supplied xattr blob one attribute at a time. For each attribute it reads a 32-bit name length, advances past the name bytes, reads a 32-bit value length, records the value pointer, and advances past the value bytes. The two length fields are read with ceph_decode_32_safe(), but the value bytes themselves are advanced over with a bare "p += len" and no ceph_decode_need() check that "len" bytes remain in the blob. For every attribute except the last, the next iteration's ceph_decode_32_safe() on the following name length implicitly verifies that the previous value did not run past the blob end. The final attribute has no successor, so its decoded value length is never checked against the blob bounds. A malicious or compromised metadata server can set the last attribute's value length larger than the bytes actually present in the blob. The blob is a dedicated kvmalloc() allocation sized to the wire length (ceph_buffer_new() in ceph_fill_inode()). __set_xattr() records the oversized length in xattr->val_len verbatim, and a later getxattr(2) runs memcpy(value, xattr->val, xattr->val_len) into a user-supplied buffer, copying bytes past the end of the allocation back to user space. Impact: a malicious metadata server discloses adjacent kernel heap bytes to a local user via getxattr(2) on a CephFS file. Add the missing ceph_decode_need() so an out-of-bounds value length on the final attribute fails the decode and returns -EIO instead of being stored.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会开源的一个操作系统内核。 Linux kernel存在安全漏洞，该漏洞源于__build_xattrs()在解码MDS提供的xattr blob时未检查最后一个属性的值长度是否超出blob边界，导致恶意元数据服务器可设置过大的值长度，后续对CephFS文件的getxattr(2)调用可能将相邻内核堆内存字节复制到用户空间，造成信息泄露。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux 355da1eb7a1f91c276b991764e951bbcd8047599 ~ 848b80ca6b410f350d08b8ac19a00ef88223f2ea -
Linux Linux 2.6.34 -

II. Public POCs for CVE-2026-89649

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III. Intelligence Information for CVE-2026-89649

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Patches & Fixes for CVE-2026-89649 (8)

Same Patch Batch · Linux · 2026-09-11 · 431 CVEs total

CVE-2026-89688 9.8 CRITICAL nfsd: drop the stateid, not the stateowner, on seqid_op replay retry
CVE-2026-89656 9.8 CRITICAL libceph: reject buckets with mismatched CRUSH ids
CVE-2026-89655 9.8 CRITICAL ceph: fix UAF in __kick_flushing_caps() on cf entry freed during unlock
CVE-2026-89658 9.8 CRITICAL NFSD: Prevent client use-after-free during NFSv4.0 revoked-state cleanup
CVE-2026-89660 9.8 CRITICAL NFSD: Prevent client use-after-free during admin state revocation
CVE-2026-89659 9.8 CRITICAL NFSD: Prevent client use-after-free during delegation revoke
CVE-2026-89662 9.8 CRITICAL NFSD: Prevent lock owner use-after-free during client teardown
CVE-2026-89669 9.8 CRITICAL nfsd: initialize copy-notify stateid before publishing it
CVE-2026-89674 9.8 CRITICAL nfsd: fix XDR length calculation in nfsd4_ff_encode_layoutget
CVE-2026-89675 9.8 CRITICAL nfsd: fix UAF in async copy cancel and shutdown
CVE-2026-89676 9.8 CRITICAL nfsd: fix stale s2s_cp_stateids IDR entry for async COPY
CVE-2026-89677 9.8 CRITICAL nfsd: fix possible fh_compose of wrong dentry in nfsd4_create_file()
CVE-2026-89681 9.8 CRITICAL nfsd: fix layout fence worker double-reference race
CVE-2026-89686 9.8 CRITICAL nfsd: fix BUG_ON in nfsd4_alloc_layout_stateid on racing delegation revoke
CVE-2026-89703 9.8 CRITICAL nfsd: set SC_STATUS_FREED in nfsd4_drop_revoked_stid for delegations
CVE-2026-89479 9.8 CRITICAL sctp: stop processing a packet once its association is deleted
CVE-2026-89478 9.8 CRITICAL sctp: drop a chunk if its transport was removed
CVE-2026-89702 9.8 CRITICAL nfsd: size fh_verify server sockaddr slot by xpt_locallen
CVE-2026-89482 9.8 CRITICAL nvme-tcp: do not accept C2HData based on blk_rq_payload_bytes() alone
CVE-2026-89708 9.8 CRITICAL nfsd: RCU-protect cl_cb_session to fix use-after-free on session teardown

Showing top 20 of 431 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

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Same vendor: Linux

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