CVE-2024-56558: Linux kernel · nfsd: make sure exp active before svc_export_show
Source GCVE Database
Not known to be exploited · CVSS 7.8 High.
Data as of 30 Oct 2026, 00:48 UTC
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 27 Dec 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
AI-suggested
A fix is available as this issue has been resolved in the Linux kernel source. Users should update their Linux kernel to a version that includes this patch. Since this is not a cloud service, manual patching or kernel upgrade is required to mitigate the vulnerability.
Description
CVE-2024-56558 is a use-after-free vulnerability in the Linux kernel's NFS daemon (nfsd). The issue arises because the function e_show was called with only RCU protection, which prevents freeing but does not prevent the reference count from dropping to zero. This can lead to a refcount use-after-free warning when exp_get is called. The flaw was fixed by using cache_get_rcu to ensure the exp object remains active during access.
References
- nvd.nist.gov/vuln/detail/CVE-2024-56558 (opens in a new tab)
- git.kernel.org/stable/c/1cecfdbc6bfc89c516d286884c7f29267b95de2b (opens in a new tab)
- git.kernel.org/stable/c/6cefcadd34e3c71c81ea64b899a0daa86314a51a (opens in a new tab)
- git.kernel.org/stable/c/7365d1f8de63cffdbbaa2287ce0205438e1a922f (opens in a new tab)
- git.kernel.org/stable/c/7d8f7816bebcd2e7400bb4d786eccb8f33c9f9ec (opens in a new tab)
- git.kernel.org/stable/c/7fd29d284b55c2274f7a748e6c5f25b4758b8da5 (opens in a new tab)
- git.kernel.org/stable/c/be8f982c369c965faffa198b46060f8853e0f1f0 (opens in a new tab)
- git.kernel.org/stable/c/e2fa0d0e327279a8defb87b263cd0bf288fd9261 (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/03/msg00001.html (opens in a new tab)
- lists.debian.org/debian-lts-announce/2025/03/msg00002.html (opens in a new tab)