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CVE-2026-43106 (GCVE-0-2026-43106)

Vulnerability from cvelistv5 – Published: 2026-05-06 07:40 – Updated: 2026-08-05 12:25
VLAI
Title
cachefiles: fix incorrect dentry refcount in cachefiles_cull()
Summary
In the Linux kernel, the following vulnerability has been resolved: cachefiles: fix incorrect dentry refcount in cachefiles_cull() The patch mentioned below changed cachefiles_bury_object() to expect 2 references to the 'rep' dentry. Three of the callers were changed to use start_removing_dentry() which takes an extra reference so in those cases the call gets the expected references. However there is another call to cachefiles_bury_object() in cachefiles_cull() which did not need to be changed to use start_removing_dentry() and so was not properly considered. It still passed the dentry with just one reference so the net result is that a reference is lost. To meet the expectations of cachefiles_bury_object(), cachefiles_cull() must take an extra reference before the call. It will be dropped by cachefiles_bury_object().
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 7bb1eb45e43c4730cbc5a48b9e9295049fccdacb , < 6577df7dc7a7de128442b6192c7a32195c923480 (git)
Affected: 7bb1eb45e43c4730cbc5a48b9e9295049fccdacb , < 1635c2acdde86c4f555b627aec873c8677c421ed (git)
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Linux Linux Affected: 6.19
Unaffected: 0 , < 6.19 (semver)
Unaffected: 6.19.14 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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          "product": "Linux",
          "programFiles": [
            "fs/cachefiles/namei.c"
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              "value": "AV:L - The vulnerable path is reached through local CacheFiles/cachefilesd activity and the `/dev/cachefiles` control interface, not by directly processing remote packets.\nAC:L - The refcount bug is deterministic once a cull operation reaches `cachefiles_cull()`; there is no attacker-uncontrolled race required, and cache pressure/cullable objects can be induced in a normal CacheFiles-backed deployment.\nPR:L - Directly opening `/dev/cachefiles` requires init-namespace `CAP_SYS_ADMIN`, but culling is normally performed by the privileged cachefilesd daemon in response to cache pressure. A local unprivileged user with access to a CacheFiles-backed mount can plausibly create cache pressure and cullable objects that cause the daemon to trigger the vulnerable command.\nUI:N - No victim user action is required once the attacker can generate the local cache activity; cachefilesd culling is daemon-driven.\nS:U - The vulnerability corrupts kernel/VFS state within the same operating-system security authority and does not cross a VM, IOMMU, or similar boundary.\nC:H - The missing extra dentry reference can produce a use-after-free/double-put on a kernel dentry. Under the required kernel guidance, UAF memory corruption is scored as capable of high confidentiality impact.\nI:H - The freed dentry can be reused while still dereferenced or put again, making this kernel memory corruption. Under the required guidance, UAFs are treated as potentially enabling arbitrary write/control-flow impact.\nA:H - The dentry refcount loss can lead to use-after-free, refcount underflow, or invalid dput paths in the kernel. Such corruption can reliably crash or oops the kernel, so availability impact is high."
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    "dateReserved": "2026-05-01T14:12:55.986Z",
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      "cve": "CVE-2026-43106",
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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.


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Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.