{"attribution":"This product uses data from the NVD API but is not endorsed or certified by the NVD.","cve":{"id":"CVE-2026-98158","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","published":"2026-09-25T11:17:47.510","lastModified":"2026-10-20T18:04:25.047","vulnStatus":"Analyzed","cveTags":[],"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nppp_async: drop the errored frame instead of resetting its headroom\n\nppp_receive_nonmp_frame() prepends a two-byte direction tag before running\nthe pass/active BPF filters:\n\n\t*(__be16 *)skb_push(skb, 2) = htons(PPP_FILTER_INBOUND_TAG);\n\nNothing on the receive path guarantees those two bytes of headroom. The\nframe-error path in ppp_async's process_input_packet() resets a reused skb's\nheadroom to zero while claiming to restore it to a freshly allocated state -\nbut a fresh skb from dev_alloc_skb() carries NET_SKB_PAD:\n\n\terr:\n\t\tif (skb) {\n\t\t\t/* make skb appear as freshly allocated */\n\t\t\tskb_trim(skb, 0);\n\t\t\tskb_reserve(skb, - skb_headroom(skb));\n\t\t}\n\nap-\u003erpkt still points at that skb, so the next frame is reassembled into it\nwith no headroom at all. A peer that sends a bad-FCS frame followed by one\nbeginning ff 03 then leaves a single byte of headroom by the time the filter\ntag is pushed, which lands one byte below skb-\u003ehead:\n\n  skbuff: skb_under_panic: len:49 put:2 head:ffff888003c10000\n          data:ffff888003c0ffff tail:0x30 end:0x640 dev:\u003cNULL\u003e\n  kernel BUG at net/core/skbuff.c:214!\n  RIP: 0010:skb_panic+0x13e/0x230\n  Call Trace:\n   skb_push+0xbd/0x100\n   ppp_receive_nonmp_frame+0x48a/0x1d10\n   ppp_input+0x4e9/0x2f80\n   ppp_async_process+0x2a/0xe0\n   tasklet_action_common+0x20f/0x8a0\n   handle_softirqs+0x18e/0x590\n  Kernel panic - not syncing: Fatal exception in interrupt\n\nZeroing the headroom violates the NET_SKB_PAD guarantee that dev_alloc_skb()\ngives the rest of the receive path. Besides the filter panic above, when CCP\ncompression is enabled ppp_decompress_frame() hands skb-\u003edata - 2 to\n-\u003edecompress()/-\u003eincomp(), which then reads out of bounds before skb-\u003ehead\nfor the same reason.\n\nRather than restore the headroom, drop the errored frame - as ppp_synctty\nalready does on its error path - and clear ap-\u003erpkt so the next frame is\nreassembled into a fresh skb with proper headroom. This is simpler and fixes\nboth the filter under-panic and the CCP out-of-bounds read.\n\nThe original V1 of this patch made room in ppp_receive_nonmp_frame() with\nskb_cow_head(); Eric pointed out that fixing the root cause in the transport\nis the right approach.\n\nFound by fuzzing the PPP receive path with a mutating peer on a pty; it is an\ninteresting (remote) DoS: root configures PPP, the peer supplies two crashing\nframes. The reproducer (repro-ppp-skb.c, unchanged from v1) panics in about a\nsecond, and returns cleanly with this applied."}],"affected":[{"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","affectedData":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","programFiles":["drivers/net/ppp/ppp_async.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","versions":[{"version":"6722e78c90054101e6797d5944cdc81af9897a0a","lessThan":"25f354c55b8435d1f51b8a0a05a3cfe429358523","versionType":"git","status":"affected"},{"version":"6722e78c90054101e6797d5944cdc81af9897a0a","lessThan":"a86a17745c3e1c6fadd4d6e90c03552dfe531c8c","versionType":"git","status":"affected"},{"version":"6722e78c90054101e6797d5944cdc81af9897a0a","lessThan":"ff035780adb0f49dc2c7ada26b4697849a68bec8","versionType":"git","status":"affected"},{"version":"6722e78c90054101e6797d5944cdc81af9897a0a","lessThan":"c4bb894362d224b699e2f95c6c26707d9654e4a3","versionType":"git","status":"affected"},{"version":"6722e78c90054101e6797d5944cdc81af9897a0a","lessThan":"d0fc3dabfe67caf084e7119ceb2ee23f5ad2f2da","versionType":"git","status":"affected"},{"version":"6722e78c90054101e6797d5944cdc81af9897a0a","lessThan":"0c53eb14975f029abd6b26896a460f0d2aaefe6b","versionType":"git","status":"affected"},{"version":"6722e78c90054101e6797d5944cdc81af9897a0a","lessThan":"717137221c7d90e7c98bda9a370c9da6cbf015e5","versionType":"git","status":"affected"},{"version":"6722e78c90054101e6797d5944cdc81af9897a0a","lessThan":"8dc5d98a16fa23c00999aecf10018c9f69fa5bf4","versionType":"git","status":"affected"}]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","programFiles":["drivers/net/ppp/ppp_async.c"],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","versions":[{"version":"2.6.15","status":"affected"},{"version":"0","lessThan":"2.6.15","versionType":"semver","status":"unaffected"},{"version":"5.10.271","lessThanOrEqual":"5.10.*","versionType":"semver","status":"unaffected"},{"version":"5.15.222","lessThanOrEqual":"5.15.*","versionType":"semver","status":"unaffected"},{"version":"6.1.189","lessThanOrEqual":"6.1.*","versionType":"semver","status":"unaffected"},{"version":"6.6.158","lessThanOrEqual":"6.6.*","versionType":"semver","status":"unaffected"},{"version":"6.12.111","lessThanOrEqual":"6.12.*","versionType":"semver","status":"unaffected"},{"version":"6.18.53","lessThanOrEqual":"6.18.*","versionType":"semver","status":"unaffected"},{"version":"7.2.7","lessThanOrEqual":"7.2.*","versionType":"semver","status":"unaffected"},{"version":"7.3","lessThanOrEqual":"*","versionType":"original_commit_for_fix","status":"unaffected"}]}]}],"metrics":{"cvssMetricV31":[{"source":"nvd@nist.gov","type":"Primary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","baseScore":5.5,"baseSeverity":"MEDIUM","attackVector":"LOCAL","attackComplexity":"LOW","privilegesRequired":"LOW","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"NONE","integrityImpact":"NONE","availabilityImpact":"HIGH"},"exploitabilityScore":1.8,"impactScore":3.6}]},"weaknesses":[{"source":"nvd@nist.gov","type":"Primary","description":[{"lang":"en","value":"CWE-125"}]}],"configurations":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"2.6.15","versionEndExcluding":"5.10.271","matchCriteriaId":"E40722F7-1496-40A6-AF08-E445B9BB75D6"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.15","versionEndExcluding":"5.15.222","matchCriteriaId":"71A72718-B484-4334-A55F-4AEF4DC98732"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.1","versionEndExcluding":"6.1.189","matchCriteriaId":"A08955FE-5938-4F5B-B6A0-BEA8BA740A26"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.6","versionEndExcluding":"6.6.158","matchCriteriaId":"4F4B14AC-C632-4A61-9E23-076CC1A04CEA"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.12","versionEndExcluding":"6.12.111","matchCriteriaId":"25101E3A-E888-4430-B5C5-6D6BC4635597"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.13","versionEndExcluding":"6.18.53","matchCriteriaId":"7561AABB-6D5A-4324-BC66-C6C6B012AFD8"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"6.19","versionEndExcluding":"7.2.7","matchCriteriaId":"19917B2D-B4B2-4416-A482-9C7C4929A921"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.3:rc1:*:*:*:*:*:*","matchCriteriaId":"11E35E1B-5DB4-4AB9-9706-CD73B799EADF"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:7.3:rc2:*:*:*:*:*:*","matchCriteriaId":"14FD7B9A-4946-4511-8E63-6E13870CD4A8"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/0c53eb14975f029abd6b26896a460f0d2aaefe6b","source":"416baaa9-dc9f-4396-8d5f-8c081fb0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