{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2021-47607 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2021-47607 is a medium-severity vulnerability in Linux kernel, published on 19 Jun 2024. It can only be exploited from the same machine or local network, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2021-47607 and fix it if it is affected.\n\nWhat it is: CVE-2021-47607 is a medium-severity vulnerability in Linux kernel, published on 19 Jun 2024. It can only be exploited from the same machine or local network, with no action from the victim.\nExploitation: There is no known exploitation of CVE-2021-47607 in the wild and no public exploit code.\n\nAffected product: Linux kernel. No package-level version data is available, so check the vendor advisory linked from the reference page.\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2021-47607/ (Markdown: https://insights.sbomify.com/CVE-2021-47607/index.md)","id":"CVE-2021-47607","markdown":"https://insights.sbomify.com/CVE-2021-47607/index.md","name":"CVE-2021-47607","record":{"aliases":["DEBIAN-CVE-2021-47607","GHSA-fp67-w4xm-4hj6","UBUNTU-CVE-2021-47607"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["data_read"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel","requires_auth":"low_privilege","summary":"An unprivileged user can leak kernel pointers via BPF atomic cmpxchg operations, potentially aiding further attacks.","user_interaction":"not_required","vuln_class":"information_disclosure"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"Linux","cpe":[{"product":"linux_kernel","vendor":"linux"}],"cvss":{"score":5.5,"severity":"medium","source":"nvd","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N","version":"3.1"},"cwes":[],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Fix kernel address leakage in atomic cmpxchg's r0 aux reg\n\nThe implementation of BPF_CMPXCHG on a high level has the following parameters:\n\n  .-[old-val]                                          .-[new-val]\n  BPF_R0 = cmpxchg{32,64}(DST_REG + insn-\u003eoff, BPF_R0, SRC_REG)\n                          `-[mem-loc]          `-[old-val]\n\nGiven a BPF insn can only have two registers (dst, src), the R0 is fixed and\nused as an auxilliary register for input (old value) as well as output (returning\nold value from memory location). While the verifier performs a number of safety\nchecks, it misses to reject unprivileged programs where R0 contains a pointer as\nold value.\n\nThrough brute-forcing it takes about ~16sec on my machine to leak a kernel pointer\nwith BPF_CMPXCHG. The PoC is basically probing for kernel addresses by storing the\nguessed address into the map slot as a scalar, and using the map value pointer as\nR0 while SRC_REG has a canary value to detect a matching address.\n\nFix it by checking R0 for pointers, and reject if that's the case for unprivileged\nprograms.","ecosystems":[],"exploits":{"exploitdb":0,"first_seen":null,"github_poc":0,"max_poc_stars":null,"metasploit":0,"nuclei":0,"refs":[],"tier":"none_known"},"has_fix":true,"headline":"bpf: Fix kernel address leakage in atomic cmpxchg's r0 aux reg","id":"CVE-2021-47607","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"information_disclosure","year":"2021"},"n_packages":0,"n_references":2,"next":{"headline":"bpf: Fix kernel address leakage in atomic fetch","id":"CVE-2021-47608"},"packages":[],"prev":{"headline":"net: netlink: af_netlink: Prevent empty skb by adding a check on len.","id":"CVE-2021-47606"},"products":["Linux"],"published":"2024-06-19","related":[{"cvss_score":8.8,"headline":"Linux Kernel Out-of-Bounds Write","id":"CVE-2026-53266","kev_date_added":"2026-09-18","published":"2026-06-25"},{"cvss_score":8.8,"headline":"Linux Kernel Improper Input Validation","id":"CVE-2013-6282","kev_date_added":"2022-09-15","published":"2013-11-19"},{"cvss_score":8.4,"headline":"Linux Kernel Heap-Based Buffer Overflow","id":"CVE-2022-0185","kev_date_added":"2024-08-21","published":"2022-02-11"},{"cvss_score":8.4,"headline":"Linux Kernel Privilege Escalation","id":"CVE-2013-2094","kev_date_added":"2022-09-15","published":"2013-05-14"},{"cvss_score":7.8,"headline":"Linux Kernel Unspecified","id":"CVE-2026-53362","kev_date_added":"2026-08-27","published":"2026-07-04"},{"cvss_score":7.8,"headline":"Linux Kernel Missing Initialization of a Variable","id":"CVE-2026-46300","kev_date_added":"2026-10-28","published":"2026-05-23"},{"cvss_score":7.8,"headline":"Linux Kernel Race Condition","id":"CVE-2025-39964","kev_date_added":"2026-09-18","published":"2025-10-13"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":"no","exploitation":"none","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-05-11","vendors":["Linux"]},"summary":"An unprivileged user can leak kernel pointers via BPF atomic cmpxchg operations, potentially aiding further attacks.","url":"https://insights.sbomify.com/CVE-2021-47607/"}