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CVE-2026-89459 (GCVE-0-2026-89459)

Vulnerability from cvelistv5 – Published: 2026-09-11 19:43 – Updated: 2026-09-13 06:29
VLAI
Title
s390/percpu: Fix MVIY_PERCPU() with older binutils
Summary
In the Linux kernel, the following vulnerability has been resolved: s390/percpu: Fix MVIY_PERCPU() with older binutils Commit a737737cdb9c ("s390/percpu: Infrastructure for more efficient this_cpu operations") introduced MVIY_PERCPU(), which stringifies arguments that are already C string literals. This generates an assembler macro invocation with whitespace-separated quoted arguments: GEN_MVIY "459712" "%r3" GNU as versions prior to binutils 2.39 drop the separating whitespace between quoted macro arguments during input scrubbing. They consequently parse the invocation as a single argument and emit repeated warnings: Warning: missing closing `"' The .ifc in GEN_MVIY never matches and GNU as exits successfully without emitting the mviy instruction. As a result, the interrupted per-CPU sequence is not marked in lowcore and the exception return path cannot repair the per-CPU address register after migration. All MVIY_PERCPU() callers pass C string literals. Use them directly and separate the assembler macro arguments with an explicit comma. The resulting invocation is: GEN_MVIY 459712, %r3 This form is unambiguous for GNU as and LLVM's integrated assembler. This behavior was fixed in GNU as from binutils 2.39, but Linux supports binutils 2.30.
Severity
7 (High)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: a737737cdb9c94e40a9926cdc2320f874c05d709 , < 91770b08a120967077ae78600612f18bc5ee3caf (git)
Affected: a737737cdb9c94e40a9926cdc2320f874c05d709 , < 101782f8945a125044347312d74d488c05741c4a (git)
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Linux Linux Affected: 7.2
Unaffected: 0 , < 7.2 (semver)
Unaffected: 7.2.4 , ≤ 7.2.* (semver)
Unaffected: 7.3-rc1 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
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{
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          "product": "Linux",
          "programFiles": [
            "arch/s390/include/asm/percpu.h"
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              "value": "AV:L - The omitted mviy start marker is in s390 this_cpu_read/write/add sequences reached from local syscalls (mm/swap, memcg, vmalloc) and user-namespace nftables; this is an arch per-CPU primitive, not a packet parser, ksmbd/nfsd handler, or USB path.\nAC:H - The op is wrong only if an interrupt or preemption and a CPU migration both occur after AG adds the old CPU offset and before the atomic instruction; that one-instruction window is not attacker-timed, even with affinity bouncing on default PREEMPT_LAZY s390.\nPR:L - Any unprivileged local user can drive this_cpu_* via ordinary syscalls, and nft_ct\u0027s this_cpu_read(nft_ct_pcpu_template) is reachable with CAP_NET_ADMIN in a user namespace; init-namespace root is not required.\nUI:N - The attacker triggers the unmarked this_cpu sequences from their own process (syscalls or locally generated packets); no victim mount, file open, or other interaction is required.\nS:U - Stale per-CPU pointers are used inside the same host kernel after migration; this is not a KVM/Xen guest-to-host escape or IOMMU/DMA boundary bypass.\nC:H - After migration, this_cpu_read uses another CPU\u0027s pointer-typed slots (percpu_swap_cluster.si, nft_ct_pcpu_template, page-pool/socket pointers) without that CPU\u0027s locking, which can disclose kernel objects and is memory corruption leverageable for info disclosure.\nI:H - The matching this_cpu_write/add then mutates the previous CPU\u0027s per-CPU state (swap cluster cache, conntrack templates, other CPU-local structures that assume exclusive access), which is kernel memory corruption exploitable toward control-flow hijack.\nA:H - A stale per-CPU pointer after migration can oops or panic (NULL vmalloc ne_fit_preload_node, inconsistent swap_info, conntrack refcount UAF), which is a full kernel availability loss on SMP s390."
            }
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-89459",
    "datePublished": "2026-09-11T19:43:22.007Z",
    "dateReserved": "2026-09-11T19:38:34.707Z",
    "dateUpdated": "2026-09-13T06:29:33.766Z",
    "state": "PUBLISHED"
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    "redhat_vex": {
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      "status": "final",
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      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-89459.json",
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      "cve": "CVE-2026-89459",
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}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.