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CVE-2026-80557— libceph: fix OOB read in decode_watchers() via missing bounds check

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 内核中已修复以下漏洞： libceph：修复 decode_watchers() 中因缺少边界检查导致的越界读取（OOB read） 会验证在编码头之后缓冲区中剩余 字节，但允许 作为有效值： 始终通过。当恶意或失陷的 OSD 发送一个 的 响应时， 会在 的情况下返回成功，导致后续读取没有保证任何可用字节。 紧随其后的 中的 前面没有进行边界检查。当 时，这将导致在已验证的缓冲区边界之外进行 4 字节的读取。这个垃圾值随后被直接传递给 作为观察者数量。 其姊妹函数 在自身的 调用之后，已经使用了安全变

AI Predicted 5.5 Difficulty: Moderate

Possible ATT&CK Techniques 1 AI

T1190 · Exploit Public-Facing Application

Affected Version Matrix 6

VendorProduct Version RangeStatus
Linux Linux a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c< 7130d94846dadbb97b6b7f4d78a3a7bba6e3daa1 affected
a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c< 00ead17c7de137a692edee59f2772e6af687e8eb affected
4.9 affected
< 4.9 unaffected
7.1.10≤ 7.1.* unaffected
7.2≤ * unaffected
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I. Basic Information for CVE-2026-80557

Vulnerability Information
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Vulnerability Title
libceph: fix OOB read in decode_watchers() via missing bounds check
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: libceph: fix OOB read in decode_watchers() via missing bounds check ceph_start_decoding() validates that struct_len bytes remain in the buffer after the encoding header, but accepts struct_len=0 as valid: ceph_decode_need(p, end, 0, bad) always passes. When a malicious or compromised OSD sends an obj_list_watch_response_t reply with struct_len=0, ceph_start_decoding() returns success with p == end, leaving zero bytes guaranteed for subsequent reads. The immediately following ceph_decode_32(p) in decode_watchers() has no preceding bounds check. With p == end this is a 4-byte read past the validated buffer boundary. The garbage value is then passed directly to kzalloc_objs() as the watcher count. The sibling function decode_watcher() already uses the safe variants (ceph_decode_copy_safe, ceph_decode_64_safe, ceph_decode_skip_32) after its own ceph_start_decoding() call. decode_watchers() is the only site that uses the bare variant, confirming an oversight. Fix by replacing ceph_decode_32(p) with ceph_decode_32_safe(p, end, *num_watchers, bad), consistent with the established pattern. Attacker model: a malicious or compromised OSD in a multi-tenant Ceph deployment (e.g. cloud) can trigger this against any kernel client that calls CEPH_OSD_OP_LIST_WATCHERS, without any further privileges beyond OSD session establishment. [ idryomov: trim changelog ]
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux a4ed38d7a180f184a6e7aedd09db9ca4b1e6a71c ~ 7130d94846dadbb97b6b7f4d78a3a7bba6e3daa1 -
Linux Linux 4.9 -

II. Public POCs for CVE-2026-80557

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III. Intelligence Information for CVE-2026-80557

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Patches & Fixes for CVE-2026-80557 (2)

Same Patch Batch · Linux · 2026-08-26 · 92 CVEs total

CVE-2026-80556 mmc: atmel-mci: Fix use-after-free in atmci_remove due to race condition
CVE-2026-80553 s390/vfio_ccw: Cancel existing workqueues
CVE-2026-80552 s390/vfio_ccw: Ensure index for read/write regions are within range
CVE-2026-80549 s390/vfio_ccw: Move cp cleanup out of not operational
CVE-2026-80546 s390/zcrypt: Improve CCA CPRB length and overflow checks
CVE-2026-80547 s390/vfio_ccw: Implement a crw lock
CVE-2026-80545 s390/zcrypt: Improve EP11 CPRB length and overflow checks
CVE-2026-80543 s390/zcrypt: Pad trailing CCA or EP11 message with zeros
CVE-2026-80548 s390/vfio_ccw: Selectively expand io_mutex
CVE-2026-80555 s390/vfio_ccw: Free all memory if cp_init() fails
CVE-2026-80554 s390/vfio_ccw: Limit the number of channel program segments
CVE-2026-80559 Input: sur40 - fix input device registration ordering
CVE-2026-80558 libceph: Avoid using invalid osd indices from primary_temp
CVE-2026-80560 openrisc: signal: do not restore privileged SR bits on sigreturn
CVE-2026-80561 libceph: fix multiple unsafe decodes in decode_locker()
CVE-2026-80562 gpio: ml-ioh: use raw_spinlock_t for the register lock
CVE-2026-80563 gpio: sloppy-logic-analyzer: fix use-after-free via debugfs trigger on unbind
CVE-2026-80564 gve: fix NULL dereference due to missing ptp adjfine
CVE-2026-80565 crypto: qce - fix error path in devm_qce_register_algs
CVE-2026-80566 Input: hynitron_cstxxx - validate touch count and finger IDs

Showing top 20 of 92 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

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