{"cve":"CVE-2023-53667","nvd":{"published":"2025-10-07T16:15:50.513","modified":"2026-06-17T06:45:49.863","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: cdc_ncm: Deal with too low values of dwNtbOutMaxSize\n\nCurrently in cdc_ncm_check_tx_max(), if dwNtbOutMaxSize is lower than\nthe calculated \"min\" value, but greater than zero, the logic sets\ntx_max to dwNtbOutMaxSize. This is then used to allocate a new SKB in\ncdc_ncm_fill_tx_frame() where all the data is handled.\n\nFor small values of dwNtbOutMaxSize the memory allocated during\nalloc_skb(dwNtbOutMaxSize, GFP_ATOMIC) will have the same size, due to\nhow size is aligned at alloc time:\n\tsize = SKB_DATA_ALIGN(size);\n        size += SKB_DATA_ALIGN(sizeof(struct skb_shared_info));\nThus we hit the same bug that we tried to squash with\ncommit 2be6d4d16a084 (\"net: cdc_ncm: Allow for dwNtbOutMaxSize to be unset or zero\")\n\nLow values of dwNtbOutMaxSize do not cause an issue presently because at\nalloc_skb() time more memory (512b) is allocated than required for the\nSKB headers alone (320b), leaving some space (512b - 320b = 192b)\nfor CDC data (172b).\n\nHowever, if more elements (for example 3 x u64 = [24b]) were added to\none of the SKB header structs, say 'struct skb_shared_info',\nincreasing its original size (320b [320b aligned]) to something larger\n(344b [384b aligned]), then suddenly the CDC data (172b) no longer\nfits in the spare SKB data area (512b - 384b = 128b).\n\nConsequently the SKB bounds checking semantics fails and panics:\n\nskbuff: skb_over_panic: text:ffffffff831f755b len:184 put:172 head:ffff88811f1c6c00 data:ffff88811f1c6c00 tail:0xb8 end:0x80 dev:<NULL>\n------------[ cut here ]------------\nkernel BUG at net/core/skbuff.c:113!\ninvalid opcode: 0000 [#1] PREEMPT SMP KASAN\nCPU: 0 PID: 57 Comm: kworker/0:2 Not tainted 5.15.106-syzkaller-00249-g19c0ed55a470 #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023\nWorkqueue: mld mld_ifc_work\nRIP: 0010:skb_panic net/core/skbuff.c:113 [inline]\nRIP: 0010:skb_over_panic+0x14c/0x150 net/core/skbuff.c:118\n[snip]\nCall Trace:\n <TASK>\n skb_put+0x151/0x210 net/core/skbuff.c:2047\n skb_put_zero include/linux/skbuff.h:2422 [inline]\n cdc_ncm_ndp16 drivers/net/usb/cdc_ncm.c:1131 [inline]\n cdc_ncm_fill_tx_frame+0x11ab/0x3da0 drivers/net/usb/cdc_ncm.c:1308\n cdc_ncm_tx_fixup+0xa3/0x100\n\nDeal with too low values of dwNtbOutMaxSize, clamp it in the range\n[USB_CDC_NCM_NTB_MIN_OUT_SIZE, CDC_NCM_NTB_MAX_SIZE_TX]. We ensure\nenough data space is allocated to handle CDC data by making sure\ndwNtbOutMaxSize is not smaller than USB_CDC_NCM_NTB_MIN_OUT_SIZE.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-476"],"references":["https://git.kernel.org/stable/c/2334ff0b343ba6ba7a6c0586fcc83992bbbc1776","https://git.kernel.org/stable/c/42b78c8cc774b47023d6d16d96d54cc7015e4a07","https://git.kernel.org/stable/c/6147745d43ff4e0d2c542e5b93e398ef0ee4db00","https://git.kernel.org/stable/c/72d0240b0ee4794efc683975c213e4b384fea733","https://git.kernel.org/stable/c/7e01c7f7046efc2c7c192c3619db43292b98e997"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:11:26.888974865+00:00"},"epss":{"cve":"CVE-2023-53667","score":0.00149,"percentile":0.04048,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}