# CVE-2021-47107: linux: In the Linux kernel, the following vulnerability has been resolved: NFSD: Fix READDIR buffer overflow If a client s... CVE-2021-47107 is fixed in 24 products on 1 platform, first by RHSA-2022:7683, released November 8, 2022. It is not reported as exploited. Patch Radar priority: High. - Web page: https://patchblox.com/security/cve/CVE-2021-47107 - Priority: High - CVSS: 7.8 (high) - EPSS: 0.0085 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Nov 8, 2022 ## 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. ## Where it's fixed | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | bpftool RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-abi-stablelists RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-core RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-debug RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-debug-core RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-debug-devel RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-debug-modules RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-debug-modules-extra RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-devel RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-doc RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-modules RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-modules-extra RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-tools RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-tools-libs RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-tools-libs-devel RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-zfcpdump RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-zfcpdump-core RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-zfcpdump-devel RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-zfcpdump-modules RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | kernel-zfcpdump-modules-extra RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | linux Debian 12.15 (bookworm) | 5.15.15-1 | [DEBIAN-CVE-2021-47107](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47107.md) | Mar 4, 2024 | | Linux | linux Debian 13.5 (trixie) | 5.15.15-1 | [DEBIAN-CVE-2021-47107](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47107.md) | Mar 4, 2024 | | Linux | linux Debian 14 | 5.15.15-1 | [DEBIAN-CVE-2021-47107](https://patchblox.com/security/data/fix/linux/debian-cve-2021-47107.md) | Mar 4, 2024 | | Linux | perf RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | | Linux | python3-perf RHEL 8 | 0:4.18.0-425.3.1.el8 | [RHSA-2022:7683](https://patchblox.com/security/data/fix/linux/rhsa-2022-7683.md) | Nov 8, 2022 | --- Data as of 2026-11-11T01:20:23Z UTC. 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