{"id":"CVE-2025-21910","state":"PUBLISHED","title":"wifi: cfg80211: regulatory: improve invalid hints checking","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nwifi: cfg80211: regulatory: improve invalid hints checking\n\nSyzbot keeps reporting an issue [1] that occurs when erroneous symbols\nsent from userspace get through into user_alpha2[] via\nregulatory_hint_user() call. Such invalid regulatory hints should be\nrejected.\n\nWhile a sanity check from commit 47caf685a685 (\"cfg80211: regulatory:\nreject invalid hints\") looks to be enough to deter these very cases,\nthere is a way to get around it due to 2 reasons.\n\n1) The way isalpha() works, symbols other than latin lower and\nupper letters may be used to determine a country/domain.\nFor instance, greek letters will also be considered upper/lower\nletters and for such characters isalpha() will return true as well.\nHowever, ISO-3166-1 alpha2 codes should only hold latin\ncharacters.\n\n2) While processing a user regulatory request, between\nreg_process_hint_user() and regulatory_hint_user() there happens to\nbe a call to queue_regulatory_request() which modifies letters in\nrequest->alpha2[] with toupper(). This works fine for latin symbols,\nless so for weird letter characters from the second part of _ctype[].\n\nSyzbot triggers a warning in is_user_regdom_saved() by first sending\nover an unexpected non-latin letter that gets malformed by toupper()\ninto a character that ends up failing isalpha() check.\n\nPrevent this by enhancing is_an_alpha2() to ensure that incoming\nsymbols are latin letters and nothing else.\n\n[1] Syzbot report:\n------------[ cut here ]------------\nUnexpected user alpha2: A�\nWARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 is_user_regdom_saved net/wireless/reg.c:440 [inline]\nWARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 restore_alpha2 net/wireless/reg.c:3424 [inline]\nWARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 restore_regulatory_settings+0x3c0/0x1e50 net/wireless/reg.c:3516\nModules linked in:\nCPU: 1 UID: 0 PID: 964 Comm: kworker/1:2 Not tainted 6.12.0-rc5-syzkaller-00044-gc1e939a21eb1 #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024\nWorkqueue: events_power_efficient crda_timeout_work\nRIP: 0010:is_user_regdom_saved net/wireless/reg.c:440 [inline]\nRIP: 0010:restore_alpha2 net/wireless/reg.c:3424 [inline]\nRIP: 0010:restore_regulatory_settings+0x3c0/0x1e50 net/wireless/reg.c:3516\n...\nCall Trace:\n <TASK>\n crda_timeout_work+0x27/0x50 net/wireless/reg.c:542\n process_one_work kernel/workqueue.c:3229 [inline]\n process_scheduled_works+0xa65/0x1850 kernel/workqueue.c:3310\n worker_thread+0x870/0xd30 kernel/workqueue.c:3391\n kthread+0x2f2/0x390 kernel/kthread.c:389\n ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244\n </TASK>","publishedAt":"2025-04-01T15:40:49.189Z","updatedAt":"2026-05-11T21:08:53.664Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"09d989d179d0c679043556dda77c51b41a2dae7e","status":"affected","lessThan":"62b1a9bbfebba4b4c2bb6c1ede9ef7ecee7a9ff6","versionType":"git"},{"version":"09d989d179d0c679043556dda77c51b41a2dae7e","status":"affected","lessThan":"da3f599517ef2ea851208df3229d07728d238dc5","versionType":"git"},{"version":"09d989d179d0c679043556dda77c51b41a2dae7e","status":"affected","lessThan":"6a5e3b23054cee3b92683d1467e3fa83921f5622","versionType":"git"},{"version":"09d989d179d0c679043556dda77c51b41a2dae7e","status":"affected","lessThan":"f4112cb477c727a65787a4065a75ca593bb5b2f4","versionType":"git"},{"version":"09d989d179d0c679043556dda77c51b41a2dae7e","status":"affected","lessThan":"35ef07112b61b06eb30683a6563c9f6378c02476","versionType":"git"},{"version":"09d989d179d0c679043556dda77c51b41a2dae7e","status":"affected","lessThan":"be7c5f00aa7f1344293e4d48d0e12be83a2f223d","versionType":"git"},{"version":"09d989d179d0c679043556dda77c51b41a2dae7e","status":"affected","lessThan":"17aa34c84867f6cd181a5743e1c647e7766962a6","versionType":"git"},{"version":"09d989d179d0c679043556dda77c51b41a2dae7e","status":"affected","lessThan":"59b348be7597c4a9903cb003c69e37df20c04a30","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/wireless/reg.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.34","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.34","versionType":"semver"},{"version":"5.4.291","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.235","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.179","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.131","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.83","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.19","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.13.7","status":"unaffected","lessThanOrEqual":"6.13.*","versionType":"semver"},{"version":"6.14","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/wireless/reg.c"]}],"references":["https://git.kernel.org/stable/c/62b1a9bbfebba4b4c2bb6c1ede9ef7ecee7a9ff6","https://git.kernel.org/stable/c/da3f599517ef2ea851208df3229d07728d238dc5","https://git.kernel.org/stable/c/6a5e3b23054cee3b92683d1467e3fa83921f5622","https://git.kernel.org/stable/c/f4112cb477c727a65787a4065a75ca593bb5b2f4","https://git.kernel.org/stable/c/35ef07112b61b06eb30683a6563c9f6378c02476","https://git.kernel.org/stable/c/be7c5f00aa7f1344293e4d48d0e12be83a2f223d","https://git.kernel.org/stable/c/17aa34c84867f6cd181a5743e1c647e7766962a6","https://git.kernel.org/stable/c/59b348be7597c4a9903cb003c69e37df20c04a30","https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html","https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html"],"weaknesses":[],"ingestedAt":"2026-10-29T20:08:39.238Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/21xxx/CVE-2025-21910.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-21910","state":"PUBLISHED","datePublished":"2025-04-01T15:40:49.189Z","dateUpdated":"2026-05-11T21:08:53.664Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-12-29T08:45:45.786Z"},"containers":{"cna":{"title":"wifi: cfg80211: regulatory: improve invalid hints checking","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nwifi: cfg80211: regulatory: improve invalid hints checking\n\nSyzbot keeps reporting an issue [1] that occurs when erroneous symbols\nsent from userspace get through into user_alpha2[] via\nregulatory_hint_user() call. Such invalid regulatory hints should be\nrejected.\n\nWhile a sanity check from commit 47caf685a685 (\"cfg80211: regulatory:\nreject invalid hints\") looks to be enough to deter these very cases,\nthere is a way to get around it due to 2 reasons.\n\n1) The way isalpha() works, symbols other than latin lower and\nupper letters may be used to determine a country/domain.\nFor instance, greek letters will also be considered upper/lower\nletters and for such characters isalpha() will return true as well.\nHowever, ISO-3166-1 alpha2 codes should only hold latin\ncharacters.\n\n2) While processing a user regulatory request, between\nreg_process_hint_user() and regulatory_hint_user() there happens to\nbe a call to queue_regulatory_request() which modifies letters in\nrequest->alpha2[] with toupper(). This works fine for latin symbols,\nless so for weird letter characters from the second part of _ctype[].\n\nSyzbot triggers a warning in is_user_regdom_saved() by first sending\nover an unexpected non-latin letter that gets malformed by toupper()\ninto a character that ends up failing isalpha() check.\n\nPrevent this by enhancing is_an_alpha2() to ensure that incoming\nsymbols are latin letters and nothing else.\n\n[1] Syzbot report:\n------------[ cut here ]------------\nUnexpected user alpha2: A�\nWARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 is_user_regdom_saved net/wireless/reg.c:440 [inline]\nWARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 restore_alpha2 net/wireless/reg.c:3424 [inline]\nWARNING: CPU: 1 PID: 964 at net/wireless/reg.c:442 restore_regulatory_settings+0x3c0/0x1e50 net/wireless/reg.c:3516\nModules linked in:\nCPU: 1 UID: 0 PID: 964 Comm: kworker/1:2 Not tainted 6.12.0-rc5-syzkaller-00044-gc1e939a21eb1 #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024\nWorkqueue: events_power_efficient crda_timeout_work\nRIP: 0010:is_user_regdom_saved net/wireless/reg.c:440 [inline]\nRIP: 0010:restore_alpha2 net/wireless/reg.c:3424 [inline]\nRIP: 0010:restore_regulatory_settings+0x3c0/0x1e50 net/wireless/reg.c:3516\n...\nCall Trace:\n <TASK>\n crda_timeout_work+0x27/0x50 net/wireless/reg.c:542\n process_one_work kernel/workqueue.c:3229 [inline]\n process_scheduled_works+0xa65/0x1850 kernel/workqueue.c:3310\n worker_thread+0x870/0xd30 kernel/workqueue.c:3391\n kthread+0x2f2/0x390 kernel/kthread.c:389\n ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147\n ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244\n </TASK>"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"09d989d179d0c679043556dda77c51b41a2dae7e","status":"affected","lessThan":"62b1a9bbfebba4b4c2bb6c1ede9ef7ecee7a9ff6","versionType":"git"},{"version":"09d989d179d0c679043556dda77c51b41a2dae7e","status":"affected","lessThan":"da3f599517ef2ea851208df3229d07728d238dc5","versionType":"git"},{"version":"09d989d179d0c679043556dda77c51b41a2dae7e","status":"affected","lessThan":"6a5e3b23054cee3b92683d1467e3fa83921f5622","versionType":"git"},{"version":"09d989d179d0c679043556dda77c51b41a2dae7e","status":"affected","lessThan":"f4112cb477c727a65787a4065a75ca593bb5b2f4","versionType":"git"},{"version":"09d989d179d0c679043556dda77c51b41a2dae7e","status":"affected","lessThan":"35ef07112b61b06eb30683a6563c9f6378c02476","versionType":"git"},{"version":"09d989d179d0c679043556dda77c51b41a2dae7e","status":"affected","lessThan":"be7c5f00aa7f1344293e4d48d0e12be83a2f223d","versionType":"git"},{"version":"09d989d179d0c679043556dda77c51b41a2dae7e","status":"affected","lessThan":"17aa34c84867f6cd181a5743e1c647e7766962a6","versionType":"git"},{"version":"09d989d179d0c679043556dda77c51b41a2dae7e","status":"affected","lessThan":"59b348be7597c4a9903cb003c69e37df20c04a30","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/wireless/reg.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"2.6.34","status":"affected"},{"version":"0","status":"unaffected","lessThan":"2.6.34","versionType":"semver"},{"version":"5.4.291","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.235","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.179","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.131","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.83","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.19","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.13.7","status":"unaffected","lessThanOrEqual":"6.13.*","versionType":"semver"},{"version":"6.14","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/wireless/reg.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/62b1a9bbfebba4b4c2bb6c1ede9ef7ecee7a9ff6"},{"url":"https://git.kernel.org/stable/c/da3f599517ef2ea851208df3229d07728d238dc5"},{"url":"https://git.kernel.org/stable/c/6a5e3b23054cee3b92683d1467e3fa83921f5622"},{"url":"https://git.kernel.org/stable/c/f4112cb477c727a65787a4065a75ca593bb5b2f4"},{"url":"https://git.kernel.org/stable/c/35ef07112b61b06eb30683a6563c9f6378c02476"},{"url":"https://git.kernel.org/stable/c/be7c5f00aa7f1344293e4d48d0e12be83a2f223d"},{"url":"https://git.kernel.org/stable/c/17aa34c84867f6cd181a5743e1c647e7766962a6"},{"url":"https://git.kernel.org/stable/c/59b348be7597c4a9903cb003c69e37df20c04a30"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T21:08:53.664Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.34","versionEndExcluding":"5.4.291"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.34","versionEndExcluding":"5.10.235"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.34","versionEndExcluding":"5.15.179"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.34","versionEndExcluding":"6.1.131"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.34","versionEndExcluding":"6.6.83"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.34","versionEndExcluding":"6.12.19"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.34","versionEndExcluding":"6.13.7"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.34","versionEndExcluding":"6.14"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CVE Program Container","references":[{"url":"https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"},{"url":"https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2025-11-03T19:38:56.982Z"}}]}}}