CVE-2021-47107NFSD: Fix READDIR buffer overflow
Updated under an hour ago ()
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No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 9.8 CRITICAL (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 14, 2026
- First seen by InfoSec Signals
- Oct 14, 2026
Affected products
Linux Linux linux:linux (from the name) | 37aa5e64022243e721b8334122997881177a4cfc builds before 9e291a6a28d32545ed2fd959a8165144d1724df1; from 7f87fc2d34d475225e78b7f5c4eabb121f4282b2 before eabc0aab98e5218ceecd82069b0d6fdfff5ee885; from 7f87fc2d34d475225e78b7f5c4eabb121f4282b2 before 53b1119a6e5028b125f431a0116ba73510d82a72 | CNA record |
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem siemens:simatic_s7_1500_tm_mfp_gnu_linux_subsystem (from the name) | before V1.1.1 | CISA ADP |
linux linux_kernel linux:linux_kernel | from 5.13 before 5.15.12; 5.16; 5.16; 5.16; 5.16; 5.16; 5.16 | NVD |
References
- https://git.kernel.org/stable/c/9e291a6a28d32545ed2fd959a8165144d1724df1exploit, mailing-list, patch
- https://git.kernel.org/stable/c/eabc0aab98e5218ceecd82069b0d6fdfff5ee885exploit, mailing-list, patch
- https://git.kernel.org/stable/c/53b1119a6e5028b125f431a0116ba73510d82a72exploit, mailing-list, patch
- https://cert-portal.siemens.com/productcert/html/ssa-265688.html
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.