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Linux Distros Unpatched Vulnerability : CVE-2021-47608
medium Nessus Plugin ID 248973
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Synopsis
The Linux/Unix host has one or more packages installed with a vulnerability that the vendor indicates will not be patched.Description
The Linux/Unix host has one or more packages installed that are impacted by a vulnerability without a vendor supplied patch available.- In the Linux kernel, the following vulnerability has been resolved: bpf: Fix kernel address leakage in atomic fetch The change in commit 37086bfdc737 (bpf: Propagate stack bounds to registers in atomics w/ BPF_FETCH) around check_mem_access() handling is buggy since this would allow for unprivileged users to leak kernel pointers. For example, an atomic fetch/and with -1 on a stack destination which holds a spilled pointer will migrate the spilled register type into a scalar, which can then be exported out of the program (since scalar != pointer) by dumping it into a map value. The original implementation of XADD was preventing this situation by using a double call to check_mem_access() one with BPF_READ and a subsequent one with BPF_WRITE, in both cases passing -1 as a placeholder value instead of register as per XADD semantics since it didn't contain a value fetch. The BPF_READ also included a check in check_stack_read_fixed_off() which rejects the program if the stack slot is of __is_pointer_value() if dst_regno < 0. The latter is to distinguish whether we're dealing with a regular stack spill/ fill or some arithmetical operation which is disallowed on non-scalars, see also 6e7e63cbb023 (bpf: Forbid XADD on spilled pointers for unprivileged users) for more context on check_mem_access() and its handling of placeholder value -1. One minimally intrusive option to fix the leak is for the BPF_FETCH case to initially check the BPF_READ case via check_mem_access() with -1 as register, followed by the actual load case with non-negative load_reg to propagate stack bounds to registers. (CVE-2021-47608)
Note that Nessus relies on the presence of the package as reported by the vendor.
Solution
There is no known solution at this time.See Also
Plugin Details
Severity: Medium
ID: 248973
File Name: unpatched_CVE_2021_47608.nasl
Version: 1.3
Type: local
Agent: unix
Family: Misc.
Published: 8/12/2025
Updated: 9/5/2025
Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Nessus
Risk Information
VPR
Risk Factor: Medium
Score: 4.4
CVSS v2
Risk Factor: Medium
Base Score: 6.6
Temporal Score: 4.9
Vector: CVSS2#AV:L/AC:L/Au:N/C:C/I:N/A:C
CVSS Score Source: CVE-2021-47608
CVSS v3
Risk Factor: Medium
Base Score: 5.5
Temporal Score: 4.8
Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C
Vulnerability Information
CPE: p-cpe:/a:redhat:enterprise_linux:kernel-rt-selftests-internal, p-cpe:/a:centos:centos:kernel-headers, p-cpe:/a:centos:centos:kernel-rt-modules-internal, p-cpe:/a:redhat:enterprise_linux:kernel-debug-devel, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-modules, p-cpe:/a:redhat:enterprise_linux:kernel-debug, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency-hwe-5.19, p-cpe:/a:centos:centos:kernel-rt-devel, p-cpe:/a:centos:centos:kernel-rt-selftests-internal, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.0, p-cpe:/a:redhat:enterprise_linux:bpftool, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-lowlatency-hwe-6.2, p-cpe:/a:centos:centos:bpftool, p-cpe:/a:centos:centos:kernel-core, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.11, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug, p-cpe:/a:canonical:ubuntu_linux:linux-hwe, p-cpe:/a:redhat:enterprise_linux:kernel-modules, cpe:/o:canonical:ubuntu_linux:16.04:-:lts, p-cpe:/a:redhat:enterprise_linux:kernel-tools, cpe:/o:canonical:ubuntu_linux:22.04:-:lts, p-cpe:/a:redhat:enterprise_linux:kernel-debug-modules, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.3, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-edge, p-cpe:/a:canonical:ubuntu_linux:linux-intel-5.13, cpe:/o:centos:centos:8, p-cpe:/a:centos:centos:kernel-zfcpdump-modules-internal, p-cpe:/a:redhat:enterprise_linux:kernel-rt-core, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.17, p-cpe:/a:redhat:enterprise_linux:kernel, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-modules-internal, p-cpe:/a:centos:centos:kernel-modules-extra, p-cpe:/a:centos:centos:kernel-cross-headers, p-cpe:/a:canonical:ubuntu_linux:linux-gcp, p-cpe:/a:centos:centos:kernel-doc, p-cpe:/a:canonical:ubuntu_linux:linux-gke-5.15, p-cpe:/a:centos:centos:kernel-tools-libs, p-cpe:/a:centos:centos:kernel-debug-modules, p-cpe:/a:redhat:enterprise_linux:kernel-ipaclones-internal, p-cpe:/a:centos:centos:kernel-rt-debug-kvm, p-cpe:/a:centos:centos:kernel-rt-debug-devel, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.19, p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules-internal, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-riscv, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.3, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules-extra, p-cpe:/a:redhat:enterprise_linux:perf, p-cpe:/a:redhat:enterprise_linux:kernel-abi-stablelists, p-cpe:/a:centos:centos:kernel-rt-modules, p-cpe:/a:centos:centos:kernel-tools, p-cpe:/a:centos:centos:kernel-abi-stablelists, p-cpe:/a:redhat:enterprise_linux:kernel-debug-core, p-cpe:/a:centos:centos:kernel-zfcpdump-devel, cpe:/o:redhat:enterprise_linux:8, p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules-internal, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-azure-edge, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde, p-cpe:/a:centos:centos:kernel-rt-debug-modules, p-cpe:/a:centos:centos:kernel-rt-core, p-cpe:/a:centos:centos:kernel-zfcpdump, p-cpe:/a:redhat:enterprise_linux:kernel-abi-whitelists, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-devel, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.8, p-cpe:/a:redhat:enterprise_linux:kernel-devel, p-cpe:/a:canonical:ubuntu_linux:linux-starfive-5.19, p-cpe:/a:centos:centos:kernel-rt-kvm, p-cpe:/a:canonical:ubuntu_linux:linux-azure, p-cpe:/a:redhat:enterprise_linux:kernel-rt-modules-extra, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.3, p-cpe:/a:centos:centos:kernel-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-modules, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.0, p-cpe:/a:centos:centos:kernel-rt-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-tools-libs-devel, p-cpe:/a:redhat:enterprise_linux:kernel-cross-headers, p-cpe:/a:canonical:ubuntu_linux:linux-nvidia-6.2, p-cpe:/a:centos:centos:kernel-tools-libs-devel, p-cpe:/a:centos:centos:kernel-debug, p-cpe:/a:centos:centos:kernel-selftests-internal, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.8, p-cpe:/a:centos:centos:perf, p-cpe:/a:redhat:enterprise_linux:kernel-modules-extra, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.13, p-cpe:/a:centos:centos:kernel, p-cpe:/a:redhat:enterprise_linux:python3-perf, p-cpe:/a:redhat:enterprise_linux:kernel-rt, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump, p-cpe:/a:canonical:ubuntu_linux:linux-gke, p-cpe:/a:centos:centos:kernel-debug-devel, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-kvm, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-6.2, p-cpe:/a:redhat:enterprise_linux:kernel-tools-libs, p-cpe:/a:canonical:ubuntu_linux:linux-oem, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.19, p-cpe:/a:centos:centos:kernel-rt-debug, cpe:/o:canonical:ubuntu_linux:18.04:-:lts, p-cpe:/a:canonical:ubuntu_linux:linux-gkeop-5.4, p-cpe:/a:canonical:ubuntu_linux:linux-allwinner-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-aws-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-aws-6.2, p-cpe:/a:centos:centos:kernel-modules, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.11, p-cpe:/a:redhat:enterprise_linux:kernel-modules-internal, p-cpe:/a:redhat:enterprise_linux:kernel-core, p-cpe:/a:centos:centos:kernel-rt-debug-modules-extra, p-cpe:/a:centos:centos:kernel-zfcpdump-core, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.3, p-cpe:/a:redhat:enterprise_linux:kernel-rt-debug-core, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.0, p-cpe:/a:centos:centos:kernel-zfcpdump-modules, p-cpe:/a:centos:centos:kernel-rt-debug-modules-internal, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-6.2, p-cpe:/a:redhat:enterprise_linux:kernel-headers, p-cpe:/a:canonical:ubuntu_linux:linux-azure-6.2, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.11, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.10, p-cpe:/a:canonical:ubuntu_linux:linux-raspi2, p-cpe:/a:centos:centos:kernel-debug-core, p-cpe:/a:redhat:enterprise_linux:kernel-selftests-internal, p-cpe:/a:canonical:ubuntu_linux:linux-gke-5.4, p-cpe:/a:redhat:enterprise_linux:kernel-debug-modules-extra, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-modules-extra, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.8, p-cpe:/a:redhat:enterprise_linux:kernel-rt-kvm, p-cpe:/a:centos:centos:kernel-ipaclones-internal, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.19, p-cpe:/a:redhat:enterprise_linux:kernel-doc, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-azure-5.13, p-cpe:/a:centos:centos:kernel-debug-modules-internal, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-core, p-cpe:/a:redhat:enterprise_linux:kernel-rt-devel, p-cpe:/a:canonical:ubuntu_linux:linux-gcp-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.6, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.8, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.11, p-cpe:/a:centos:centos:kernel-modules-internal, p-cpe:/a:centos:centos:kernel-rt-debug-core, p-cpe:/a:canonical:ubuntu_linux:linux-oem-6.1, cpe:/o:canonical:ubuntu_linux:20.04:-:lts, p-cpe:/a:centos:centos:python3-perf, p-cpe:/a:redhat:enterprise_linux:kernel-debug-modules-internal, p-cpe:/a:canonical:ubuntu_linux:linux-oem-5.14, p-cpe:/a:centos:centos:kernel-rt, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde-5.19, p-cpe:/a:canonical:ubuntu_linux:linux-azure-fde-6.2, p-cpe:/a:redhat:enterprise_linux:kernel-zfcpdump-devel, p-cpe:/a:canonical:ubuntu_linux:linux-oracle-5.8, p-cpe:/a:centos:centos:kernel-abi-whitelists, p-cpe:/a:canonical:ubuntu_linux:linux-hwe-5.13, p-cpe:/a:canonical:ubuntu_linux:linux-riscv-5.19, p-cpe:/a:centos:centos:kernel-zfcpdump-modules-extra, p-cpe:/a:canonical:ubuntu_linux:linux-gke-4.15, p-cpe:/a:centos:centos:kernel-debug-modules-extra, p-cpe:/a:canonical:ubuntu_linux:linux-starfive-6.2
Required KB Items: Host/local_checks_enabled, Host/cpu, global_settings/vendor_unpatched, Host/OS/identifier
Exploit Ease: No known exploits are available
Vulnerability Publication Date: 6/19/2024
Reference Information
CVE: CVE-2021-47608