{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2026-31421","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2026-03-09T15:48:24.088Z","datePublished":"2026-04-13T13:40:25.278Z","dateUpdated":"2026-05-11T22:08:22.956Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-05-11T22:08:22.956Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: cls_fw: fix NULL pointer dereference on shared blocks\n\nThe old-method path in fw_classify() calls tcf_block_q() and\ndereferences q->handle.  Shared blocks leave block->q NULL, causing a\nNULL deref when an empty cls_fw filter is attached to a shared block\nand a packet with a nonzero major skb mark is classified.\n\nReject the configuration in fw_change() when the old method (no\nTCA_OPTIONS) is used on a shared block, since fw_classify()'s\nold-method path needs block->q which is NULL for shared blocks.\n\nThe fixed null-ptr-deref calling stack:\n KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]\n RIP: 0010:fw_classify (net/sched/cls_fw.c:81)\n Call Trace:\n  tcf_classify (./include/net/tc_wrapper.h:197 net/sched/cls_api.c:1764 net/sched/cls_api.c:1860)\n  tc_run (net/core/dev.c:4401)\n  __dev_queue_xmit (net/core/dev.c:4535 net/core/dev.c:4790)"}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/cls_fw.c"],"versions":[{"version":"1abf272022cf1d18469405f47b4ec49c6a3125db","lessThan":"d6d5bd62a09650856e1e2010eb09853eba0d64e1","status":"affected","versionType":"git"},{"version":"1abf272022cf1d18469405f47b4ec49c6a3125db","lessThan":"febf64ca79a2d6540ab6e5e197fa0f4f7e84473e","status":"affected","versionType":"git"},{"version":"1abf272022cf1d18469405f47b4ec49c6a3125db","lessThan":"3d41f9a314afa94b1c7c7c75405920123220e8cd","status":"affected","versionType":"git"},{"version":"1abf272022cf1d18469405f47b4ec49c6a3125db","lessThan":"18328eff2f97d1a6adcdb6d4a0f42f2f83a31e28","status":"affected","versionType":"git"},{"version":"1abf272022cf1d18469405f47b4ec49c6a3125db","lessThan":"5cf41031922c154aa5ccda8bcdb0f5e6226582ec","status":"affected","versionType":"git"},{"version":"1abf272022cf1d18469405f47b4ec49c6a3125db","lessThan":"3cb055df9e8625ce699a259d8178d67b37f2b160","status":"affected","versionType":"git"},{"version":"1abf272022cf1d18469405f47b4ec49c6a3125db","lessThan":"96426c348def662b06bfdc65be3002905604927a","status":"affected","versionType":"git"},{"version":"1abf272022cf1d18469405f47b4ec49c6a3125db","lessThan":"faeea8bbf6e958bf3c00cb08263109661975987c","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/sched/cls_fw.c"],"versions":[{"version":"4.15","status":"affected"},{"version":"0","lessThan":"4.15","status":"unaffected","versionType":"semver"},{"version":"5.10.253","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.203","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.168","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.134","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.12.81","lessThanOrEqual":"6.12.*","status":"unaffected","versionType":"semver"},{"version":"6.18.22","lessThanOrEqual":"6.18.*","status":"unaffected","versionType":"semver"},{"version":"6.19.12","lessThanOrEqual":"6.19.*","status":"unaffected","versionType":"semver"},{"version":"7.0","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"5.10.253"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"5.15.203"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.1.168"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.6.134"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.12.81"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.18.22"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"6.19.12"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.15","versionEndExcluding":"7.0"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/d6d5bd62a09650856e1e2010eb09853eba0d64e1"},{"url":"https://git.kernel.org/stable/c/febf64ca79a2d6540ab6e5e197fa0f4f7e84473e"},{"url":"https://git.kernel.org/stable/c/3d41f9a314afa94b1c7c7c75405920123220e8cd"},{"url":"https://git.kernel.org/stable/c/18328eff2f97d1a6adcdb6d4a0f42f2f83a31e28"},{"url":"https://git.kernel.org/stable/c/5cf41031922c154aa5ccda8bcdb0f5e6226582ec"},{"url":"https://git.kernel.org/stable/c/3cb055df9e8625ce699a259d8178d67b37f2b160"},{"url":"https://git.kernel.org/stable/c/96426c348def662b06bfdc65be3002905604927a"},{"url":"https://git.kernel.org/stable/c/faeea8bbf6e958bf3c00cb08263109661975987c"}],"title":"net/sched: cls_fw: fix NULL pointer dereference on shared blocks","x_generator":{"engine":"bippy-1.2.0"}}}}