{"answers":{"affected":"It affects 1 product.","exploited":"There is no known exploitation of CVE-2025-21820 in the wild and no public exploit code.","fix":"Apply the vendor's patch.","what":"CVE-2025-21820 is a medium-severity vulnerability in Linux kernel, published on 27 Feb 2025. 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-2025-21820 and fix it if it is affected.\n\nWhat it is: CVE-2025-21820 is a medium-severity vulnerability in Linux kernel, published on 27 Feb 2025. 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-2025-21820 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-2025-21820/ (Markdown: https://insights.sbomify.com/CVE-2025-21820/index.md)","id":"CVE-2025-21820","markdown":"https://insights.sbomify.com/CVE-2025-21820/index.md","name":"CVE-2025-21820","record":{"aliases":["AZL-57749","BELL-CVE-2025-21820","DEBIAN-CVE-2025-21820","GHSA-pgjm-rqqp-m93m","ROOT-OS-DEBIAN-11-CVE-2025-21820","ROOT-OS-UBUNTU-2404-CVE-2025-21820","UBUNTU-CVE-2025-21820"],"analysis":{"component_type":"kernel","fix_type":"patch","impacts":["denial_of_service"],"network_reachable":"adjacent_or_local","non_default_config":false,"product_category":"Linux kernel driver","requires_auth":"low_privilege","summary":"A race condition in the Xilinx UART driver can cause a deadlock, leading to a denial of service.","user_interaction":"not_required","vuln_class":"race_condition"},"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:N/I:N/A:H","version":"3.1"},"cwes":[{"id":"CWE-667","name":"Improper Locking"}],"description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntty: xilinx_uartps: split sysrq handling\n\nlockdep detects the following circular locking dependency:\n\nCPU 0                      CPU 1\n========================== ============================\ncdns_uart_isr()            printk()\n  uart_port_lock(port)       console_lock()\n\t\t\t     cdns_uart_console_write()\n                               if (!port-\u003esysrq)\n                                 uart_port_lock(port)\n  uart_handle_break()\n    port-\u003esysrq = ...\n  uart_handle_sysrq_char()\n    printk()\n      console_lock()\n\nThe fixed commit attempts to avoid this situation by only taking the\nport lock in cdns_uart_console_write if port-\u003esysrq unset. However, if\n(as shown above) cdns_uart_console_write runs before port-\u003esysrq is set,\nthen it will try to take the port lock anyway. This may result in a\ndeadlock.\n\nFix this by splitting sysrq handling into two parts. We use the prepare\nhelper under the port lock and defer handling until we release the lock.","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":"tty: xilinx_uartps: split sysrq handling","id":"CVE-2025-21820","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":null,"product":"linux:linux_kernel","products":["linux:linux_kernel"],"type":"race_condition","year":"2025"},"n_packages":0,"n_references":6,"next":{"headline":"fbdev: omap: use threaded IRQ for LCD DMA","id":"CVE-2025-21821"},"packages":[],"prev":{"headline":"Revert \"drm/amd/display: Use HW lock mgr for PSR1\"","id":"CVE-2025-21819"},"products":["Linux"],"published":"2025-02-27","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":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"}],"ssvc":{"automatable":null,"exploitation":null,"technical_impact":null},"state":"PUBLISHED","updated":"2026-05-11","vendors":["Linux"]},"summary":"A race condition in the Xilinx UART driver can cause a deadlock, leading to a denial of service.","url":"https://insights.sbomify.com/CVE-2025-21820/"}