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CVE-2026-98258— posix-cpu-timers: Prevent freeing a timer which is queued on the expiry list

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.

在 Linux 内核中，以下漏洞已得到修复： posix-cpu-timers：防止释放仍处于超时列表（expiry list）中的定时器 Kijo 分析了 POSIX CPU 定时器代码中的另一个竞态条件： 提交 bf635681c906 将 从三值（tristate）改为布尔值。这丢失了“不属于 firing 列表”与“仍属于 firing 列表但投递已被取消”之间的区别。由此产生的竞态条件如下： 自该提交以来， 位显然不再是一个合适的判断依据。 因此，改为检查定时器是否仍处于超时列表中。如果定时器仍挂起在超时

CVSS 7.8 · High EPSS 0.14% · P3

Possible ATT&CK Techniques 1 AI

T1059 · Command and Scripting Interpreter

Affected Version Matrix 8

VendorProduct Version RangeStatus
Linux Linux bf635681c906ad056d1fda325de8d1c12c9f8201< 9971dac1a77845ff467146915fcbb9170f6a8209 affected
bf635681c906ad056d1fda325de8d1c12c9f8201< 4336e3f47d9d516441066e9a65eaf076790d8d45 affected
bf635681c906ad056d1fda325de8d1c12c9f8201< c21eaa72f02fc6e85621cbe09d303d8fb8bd39cd affected
6.13 affected
< 6.13 unaffected
6.18.54≤ 6.18.* unaffected
7.2.8≤ 7.2.* unaffected
7.3-rc4≤ * unaffected
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I. Basic Information for CVE-2026-98258

Vulnerability Information
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Vulnerability Title
posix-cpu-timers: Prevent freeing a timer which is queued on the expiry list
Source: CVE Program / CVE List V5
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: posix-cpu-timers: Prevent freeing a timer which is queued on the expiry list Kijo analyzed another race in the POSIX CPU timer code: Commit bf635681c906 converted cpu_timer::firing from a tristate value to a boolean. This lost the distinction between "not owned by the firing list" and "still owned, but delivery was canceled". The resulting race is: expiry handler timer_settime() timer_delete() -------------- --------------- -------------- collect timer onto private firing list firing = true observes firing = true firing = false return TIMER_RETRY wait for handler observes firing = false finish deletion unhash and free timer resume list traversal read freed elist.next -> UAF The firing bit is clearly the wrong indicator since that commit. Check whether the timer is queued on the expiry list or not instead. If it is queued clear the firing bit to prevent signal delivery as before and return TIMER_RETRY so the caller unlocks the timer which allows the expiry code to make progress and remove it from the list.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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 bf635681c906ad056d1fda325de8d1c12c9f8201 ~ 9971dac1a77845ff467146915fcbb9170f6a8209 -
Linux Linux 6.13 -

II. Public POCs for CVE-2026-98258

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III. Intelligence Information for CVE-2026-98258

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Patches & Fixes for CVE-2026-98258 (3)

Same Patch Batch · Linux · 2026-10-06 · 208 CVEs total

CVE-2026-98323 9.8 CRITICAL RDMA/siw: Bound fragmented header copies by the remaining length
CVE-2026-98365 9.8 CRITICAL RDMA/rxe: Fix integer overflow in mr_check_range() leading to OOB access
CVE-2026-98282 8.8 HIGH powerpc/iommu: Fix the overflow validation in iommu_tce_check_ioba
CVE-2026-98283 8.8 HIGH KVM: PPC: Book3S HV: fix use-after-free in kvmhv_emulate_tlbie_all_lpid()
CVE-2026-98339 8.8 HIGH wifi: cfg80211: don't filter by BSS type when removing stale entries
CVE-2026-98171 8.8 HIGH smb: client: fix next_buffer UAF and NextCommand bounds in compound PDUs
CVE-2026-98261 8.1 HIGH cifs: Fix server use-after-free in cifs_chan_skip_or_disable()
CVE-2026-98357 8.1 HIGH IB/isert: wait for deferred control PDU completions before releasing the connection
CVE-2026-98239 8.1 HIGH net: lan743x: fix RX checksum use-after-free
CVE-2026-98341 7.8 HIGH wifi: cfg80211: don't free driver-owned scan requests
CVE-2026-98324 7.8 HIGH dmaengine: pxa: fix double counting of the hw descriptors
CVE-2026-98320 7.8 HIGH netfilter: flowtable: hold reference on ct until flow is released
CVE-2026-98228 7.8 HIGH mips: select CONFIG_WEAK_REORDERING_BEYOND_LLSC from CONFIG_EYEQ
CVE-2026-98229 7.8 HIGH xfrm: save input state data before secpath resets
CVE-2026-98318 7.8 HIGH smb: client: validate absolute native symlink targets before NT fixups
CVE-2026-98315 7.8 HIGH ntfs: protect runlist updates with the runlist lock
CVE-2026-98276 7.8 HIGH net: lock the socket in sock_gettstamp()
CVE-2026-98256 7.8 HIGH signal: Prevent exec() race
CVE-2026-98260 7.8 HIGH exec: Cleanup POSIX timers right after de_thread()
CVE-2026-98254 7.8 HIGH swiotlb: use the adjusted address for the highmem page lookup

Showing top 20 of 208 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-98258

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