{"id":"CVE-2025-21857","state":"PUBLISHED","title":"net/sched: cls_api: fix error handling causing NULL dereference","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_api: fix error handling causing NULL dereference\n\ntcf_exts_miss_cookie_base_alloc() calls xa_alloc_cyclic() which can\nreturn 1 if the allocation succeeded after wrapping. This was treated as\nan error, with value 1 returned to caller tcf_exts_init_ex() which sets\nexts->actions to NULL and returns 1 to caller fl_change().\n\nfl_change() treats err == 1 as success, calling tcf_exts_validate_ex()\nwhich calls tcf_action_init() with exts->actions as argument, where it\nis dereferenced.\n\nExample trace:\n\nBUG: kernel NULL pointer dereference, address: 0000000000000000\nCPU: 114 PID: 16151 Comm: handler114 Kdump: loaded Not tainted 5.14.0-503.16.1.el9_5.x86_64 #1\nRIP: 0010:tcf_action_init+0x1f8/0x2c0\nCall Trace:\n tcf_action_init+0x1f8/0x2c0\n tcf_exts_validate_ex+0x175/0x190\n fl_change+0x537/0x1120 [cls_flower]","publishedAt":"2025-03-12T09:42:10.622Z","updatedAt":"2026-05-11T21:07:51.008Z","severity":{"score":5.5,"label":"Medium","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","source":"CISA-ADP"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"80cd22c35c9001fe72bf614d29439de41933deca","status":"affected","lessThan":"de4b679aa3b4da7ec34f639df068b914f20e3c3c","versionType":"git"},{"version":"80cd22c35c9001fe72bf614d29439de41933deca","status":"affected","lessThan":"3e4c56cf41876ef2a82f0877fe2a67648f8632b8","versionType":"git"},{"version":"80cd22c35c9001fe72bf614d29439de41933deca","status":"affected","lessThan":"3c74b5787caf59bb1e9c5fe0a360643a71eb1e8a","versionType":"git"},{"version":"80cd22c35c9001fe72bf614d29439de41933deca","status":"affected","lessThan":"071ed42cff4fcdd89025d966d48eabef59913bf2","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/cls_api.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.3","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.3","versionType":"semver"},{"version":"6.6.80","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.17","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.13.5","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/sched/cls_api.c"]}],"references":["https://git.kernel.org/stable/c/de4b679aa3b4da7ec34f639df068b914f20e3c3c","https://git.kernel.org/stable/c/3e4c56cf41876ef2a82f0877fe2a67648f8632b8","https://git.kernel.org/stable/c/3c74b5787caf59bb1e9c5fe0a360643a71eb1e8a","https://git.kernel.org/stable/c/071ed42cff4fcdd89025d966d48eabef59913bf2"],"weaknesses":["CWE-476"],"ingestedAt":"2026-10-29T20:08:39.238Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/21xxx/CVE-2025-21857.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-21857","state":"PUBLISHED","datePublished":"2025-03-12T09:42:10.622Z","dateUpdated":"2026-05-11T21:07:51.008Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-12-29T08:45:45.780Z"},"containers":{"cna":{"title":"net/sched: cls_api: fix error handling causing NULL dereference","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_api: fix error handling causing NULL dereference\n\ntcf_exts_miss_cookie_base_alloc() calls xa_alloc_cyclic() which can\nreturn 1 if the allocation succeeded after wrapping. This was treated as\nan error, with value 1 returned to caller tcf_exts_init_ex() which sets\nexts->actions to NULL and returns 1 to caller fl_change().\n\nfl_change() treats err == 1 as success, calling tcf_exts_validate_ex()\nwhich calls tcf_action_init() with exts->actions as argument, where it\nis dereferenced.\n\nExample trace:\n\nBUG: kernel NULL pointer dereference, address: 0000000000000000\nCPU: 114 PID: 16151 Comm: handler114 Kdump: loaded Not tainted 5.14.0-503.16.1.el9_5.x86_64 #1\nRIP: 0010:tcf_action_init+0x1f8/0x2c0\nCall Trace:\n tcf_action_init+0x1f8/0x2c0\n tcf_exts_validate_ex+0x175/0x190\n fl_change+0x537/0x1120 [cls_flower]"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"80cd22c35c9001fe72bf614d29439de41933deca","status":"affected","lessThan":"de4b679aa3b4da7ec34f639df068b914f20e3c3c","versionType":"git"},{"version":"80cd22c35c9001fe72bf614d29439de41933deca","status":"affected","lessThan":"3e4c56cf41876ef2a82f0877fe2a67648f8632b8","versionType":"git"},{"version":"80cd22c35c9001fe72bf614d29439de41933deca","status":"affected","lessThan":"3c74b5787caf59bb1e9c5fe0a360643a71eb1e8a","versionType":"git"},{"version":"80cd22c35c9001fe72bf614d29439de41933deca","status":"affected","lessThan":"071ed42cff4fcdd89025d966d48eabef59913bf2","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/cls_api.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"6.3","status":"affected"},{"version":"0","status":"unaffected","lessThan":"6.3","versionType":"semver"},{"version":"6.6.80","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.17","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.13.5","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/sched/cls_api.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/de4b679aa3b4da7ec34f639df068b914f20e3c3c"},{"url":"https://git.kernel.org/stable/c/3e4c56cf41876ef2a82f0877fe2a67648f8632b8"},{"url":"https://git.kernel.org/stable/c/3c74b5787caf59bb1e9c5fe0a360643a71eb1e8a"},{"url":"https://git.kernel.org/stable/c/071ed42cff4fcdd89025d966d48eabef59913bf2"}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-05-11T21:07:51.008Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"6.6.80"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"6.12.17"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"6.13.5"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.3","versionEndExcluding":"6.14"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"cvssV3_1":{"scope":"UNCHANGED","version":"3.1","baseScore":5.5,"attackVector":"LOCAL","baseSeverity":"MEDIUM","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","integrityImpact":"NONE","userInteraction":"NONE","attackComplexity":"LOW","availabilityImpact":"HIGH","privilegesRequired":"LOW","confidentialityImpact":"NONE"}},{"other":{"type":"ssvc","content":{"id":"CVE-2025-21857","role":"CISA Coordinator","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"version":"2.0.3","timestamp":"2025-10-01T19:25:55.274904Z"}}}],"problemTypes":[{"descriptions":[{"cweId":"CWE-476","lang":"en","type":"CWE","description":"CWE-476 NULL Pointer Dereference"}]}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2025-10-01T19:26:38.155Z"}}]}}}