Description
In the Linux kernel, the following vulnerability has been resolved: NFSD: Fix READDIR buffer overflow If a client sends a READDIR count argument that is too small (say, zero), then the buffer size calculation in the new init_dirlist helper functions results in an underflow, allowing the XDR stream functions to write beyond the actual buffer. This calculation has always been suspect. NFSD has never sanity- checked the READDIR count argument, but the old entry encoders managed the problem correctly. With the commits below, entry encoding changed, exposing the underflow to the pointer arithmetic in xdr_reserve_space(). Modern NFS clients attempt to retrieve as much data as possible for each READDIR request. Also, we have no unit tests that exercise the behavior of READDIR at the lower bound of @count values. Thus this case was missed during testing.
Affected products
linux: linux kernel
References7
- git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72 ExploitMailing ListPatch
- git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1 ExploitMailing ListPatch
- git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885 ExploitMailing ListPatch
- git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72 ExploitMailing ListPatch
- git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1 ExploitMailing ListPatch
- git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885 ExploitMailing ListPatch
- cert-portal.siemens.com/productcert/html/ssa-265688.html
Metrics
- CVSS 3.1
-
7.8
HIGH
Score source: NVD
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 1% percentile: 58 · as of 5 November 2026
- CWE
- CWE-120
Could this be exploited in your environment?
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