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CVE Record

CVE-2023-52438: binder: fix use-after-free in shinker's callback

In the Linux kernel, the following vulnerability has been resolved: binder: fix use-after-free in shinker's callback The mmap read lock is used during the shrinker's callback, which means that using alloc->vma pointer isn't safe as it can race with munmap(). As of commit dd2283f2605e ("mm: mmap: zap pages with read mmap_sem in munmap") the mmap lock is downgraded after the vma has been isolated. I was able to reproduce this issue by manually adding some delays and triggering page reclaiming through the shrinker's debug sysfs. The following KASAN report confirms the UAF: ================================================================== BUG: KASAN: slab-use-after-free in zap_page_range_single+0x470/0x4b8 Read of size 8 at addr ffff356ed50e50f0 by task bash/478 CPU: 1 PID: 478 Comm: bash Not tainted 6.6.0-rc5-00055-g1c8b86a3799f-dirty #70 Hardware name: linux,dummy-virt (DT) Call trace: zap_page_range_single+0x470/0x4b8 binder_alloc_free_page+0x608/0xadc __list_lru_walk_one+0x130/0x3b0 list_lru_walk_node+0xc4/0x22c binder_shrink_scan+0x108/0x1dc shrinker_debugfs_scan_write+0x2b4/0x500 full_proxy_write+0xd4/0x140 vfs_write+0x1ac/0x758 ksys_write+0xf0/0x1dc __arm64_sys_write+0x6c/0x9c Allocated by task 492: kmem_cache_alloc+0x130/0x368 vm_area_alloc+0x2c/0x190 mmap_region+0x258/0x18bc do_mmap+0x694/0xa60 vm_mmap_pgoff+0x170/0x29c ksys_mmap_pgoff+0x290/0x3a0 __arm64_sys_mmap+0xcc/0x144 Freed by task 491: kmem_cache_free+0x17c/0x3c8 vm_area_free_rcu_cb+0x74/0x98 rcu_core+0xa38/0x26d4 rcu_core_si+0x10/0x1c __do_softirq+0x2fc/0xd24 Last potentially related work creation: __call_rcu_common.constprop.0+0x6c/0xba0 call_rcu+0x10/0x1c vm_area_free+0x18/0x24 remove_vma+0xe4/0x118 do_vmi_align_munmap.isra.0+0x718/0xb5c do_vmi_munmap+0xdc/0x1fc __vm_munmap+0x10c/0x278 __arm64_sys_munmap+0x58/0x7c Fix this issue by performing instead a vma_lookup() which will fail to find the vma that was isolated before the mmap lock downgrade. Note that this option has better performance than upgrading to a mmap write lock which would increase contention. Plus, mmap_write_trylock() has been recently removed anyway.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This Linux kernel flaw can cause memory to be accessed after it has been freed during Binder memory reclamation. A local, low-privileged user could potentially compromise confidentiality, integrity, and availability. The source bundle rates it CVSS 7.8, but does not establish active exploitation.

Executive priority

Treat this as a high-priority kernel update for systems where untrusted users can run local code and reach Binder. Internet-facing status alone does not determine risk because the stated attack vector is local. Validate affected builds promptly, then deploy supported kernel updates through normal change controls.

Technical view

A race between Binder's shrinker callback and munmap() can leave binder_alloc_free_page() using an unsafe VMA pointer after isolation and lock downgrade, producing a use-after-free. The upstream correction performs vma_lookup() while holding the mmap read lock, preventing use of the isolated VMA.

Likely exposure

Exposure requires an affected Linux kernel and local access to the relevant Binder functionality. The supplied version entries do not form clear ranges, so exact exposure should be determined using kernel build details and distribution guidance rather than version-string assumptions.

Exploitation context

The CVSS vector indicates local access, low complexity, low privileges, and no user interaction, with potentially high confidentiality, integrity, and availability impact. The bundle marks KEV false and provides no evidence of exploitation in the wild; that does not prove exploitation is absent.

Researcher notes

The supplied affected-version list mixes release numbers, a zero entry, and repeated commit identifiers, limiting precise range interpretation. The reproduced KASAN trace supports the underlying use-after-free. Assess reachability through Binder configuration and permissions, and use downstream vendor backport status instead of assuming upstream version equivalence.

Mitigation direction

  • Install a vendor-supported kernel containing the applicable upstream stable fix.
  • Reboot into the updated kernel; installing a package alone may leave the vulnerable kernel running.
  • If patching is delayed, consult distribution guidance because the sources identify no separate workaround.
  • Prioritize systems permitting untrusted local users to access Binder functionality.

Validation and detection

  • Record the running kernel version, build, architecture, and distribution package revision.
  • Determine whether Binder support is present and accessible to untrusted local users.
  • Match the exact build against distribution advisories and the listed upstream stable fixes.
  • After rebooting, confirm the active kernel is the intended patched build.
  • Review kernel and KASAN logs for relevant use-after-free or Binder memory-reclamation failures.
Prepared
Confidence
medium
Sources
10

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2023-52438 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
2ADP providers
9Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2023-52438Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxdd2283f2605e3b3e9c61bcae844b34f2afa4813f, dd2283f2605e3b3e9c61bcae844b34f2afa4813f, dd2283f2605e3b3e9c61bcae844b34f2afa4813f, dd2283f2605e3b3e9c61bcae844b34f2afa4813f, dd2283f2605e3b3e9c61bcae844b34f2afa4813f, dd2283f2605e3b3e9c61bcae844b34f2afa4813f, dd2283f2605e3b3e9c61bcae844b34f2afa4813funaffected
LinuxLinux4.20, 0, 5.4.268, 5.10.209, 5.15.148, 6.1.74, 6.6.13, 6.7.1, 6.8affected
Weakness

CWE details

No CWE listed

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