{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-98158", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-09-25T10:25:14.321Z", "datePublished": "2026-09-25T10:36:27.608Z", "dateUpdated": "2026-10-19T09:14:52.068Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-10-19T09:14:52.068Z" }, "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->rpkt 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->head:\n\n skbuff: skb_under_panic: len:49 put:2 head:ffff888003c10000\n data:ffff888003c0ffff tail:0x30 end:0x640 dev:\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->data - 2 to\n->decompress()/->incomp(), which then reads out of bounds before skb->head\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->rpkt 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": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ppp/ppp_async.c" ], "versions": [ { "version": "6722e78c90054101e6797d5944cdc81af9897a0a", "lessThan": "25f354c55b8435d1f51b8a0a05a3cfe429358523", "status": "affected", "versionType": "git" }, { "version": "6722e78c90054101e6797d5944cdc81af9897a0a", "lessThan": "a86a17745c3e1c6fadd4d6e90c03552dfe531c8c", "status": "affected", "versionType": "git" }, { "version": "6722e78c90054101e6797d5944cdc81af9897a0a", "lessThan": "ff035780adb0f49dc2c7ada26b4697849a68bec8", "status": "affected", "versionType": "git" }, { "version": "6722e78c90054101e6797d5944cdc81af9897a0a", "lessThan": "c4bb894362d224b699e2f95c6c26707d9654e4a3", "status": "affected", "versionType": "git" }, { "version": "6722e78c90054101e6797d5944cdc81af9897a0a", "lessThan": "d0fc3dabfe67caf084e7119ceb2ee23f5ad2f2da", "status": "affected", "versionType": "git" }, { "version": "6722e78c90054101e6797d5944cdc81af9897a0a", "lessThan": "0c53eb14975f029abd6b26896a460f0d2aaefe6b", "status": "affected", "versionType": "git" }, { "version": "6722e78c90054101e6797d5944cdc81af9897a0a", "lessThan": "717137221c7d90e7c98bda9a370c9da6cbf015e5", "status": "affected", "versionType": "git" }, { "version": "6722e78c90054101e6797d5944cdc81af9897a0a", "lessThan": "8dc5d98a16fa23c00999aecf10018c9f69fa5bf4", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ppp/ppp_async.c" ], "versions": [ { "version": "2.6.15", "status": "affected" }, { "version": "0", "lessThan": "2.6.15", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.271", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.222", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.189", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.158", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.111", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.53", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.2.7", "lessThanOrEqual": "7.2.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.3", "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": "2.6.15", "versionEndExcluding": "5.10.271" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.15", "versionEndExcluding": "5.15.222" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.15", "versionEndExcluding": "6.1.189" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.15", "versionEndExcluding": "6.6.158" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.15", "versionEndExcluding": "6.12.111" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.15", "versionEndExcluding": "6.18.53" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.15", "versionEndExcluding": "7.2.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.15", "versionEndExcluding": "7.3" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/25f354c55b8435d1f51b8a0a05a3cfe429358523" }, { "url": "https://git.kernel.org/stable/c/a86a17745c3e1c6fadd4d6e90c03552dfe531c8c" }, { "url": "https://git.kernel.org/stable/c/ff035780adb0f49dc2c7ada26b4697849a68bec8" }, { "url": "https://git.kernel.org/stable/c/c4bb894362d224b699e2f95c6c26707d9654e4a3" }, { "url": "https://git.kernel.org/stable/c/d0fc3dabfe67caf084e7119ceb2ee23f5ad2f2da" }, { "url": "https://git.kernel.org/stable/c/0c53eb14975f029abd6b26896a460f0d2aaefe6b" }, { "url": "https://git.kernel.org/stable/c/717137221c7d90e7c98bda9a370c9da6cbf015e5" }, { "url": "https://git.kernel.org/stable/c/8dc5d98a16fa23c00999aecf10018c9f69fa5bf4" } ], "title": "ppp_async: drop the errored frame instead of resetting its headroom", "x_generator": { "engine": "bippy-1.2.0" } } } }