{"id":"CVE-2026-98457","kind":"vulnerability","aliases":["CVE-2026-98457"],"related":[],"title":"Linux kernel: short Bluetooth L2CAP frames cause out-of-bounds memory reads","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: validate frame length before control and FCS access\n\nl2cap_data_rcv() unpacks either a two-byte or four-byte control field\nwithout first ensuring that it is present. A short ERTM or streaming-mode\nframe can therefore cause an out-of-bounds read.\n\nThere is a second short-frame case when CRC16 is enabled. After the\ncontrol field is pulled, l2cap_check_fcs() subtracts two from skb->len\nwithout checking it. If fewer than two bytes remain, the subtraction\nwraps; skb_trim() leaves the buffer unchanged and the subsequent FCS\nload reads past the logical end of the frame.\n\nValidate that the frame contains both its control field and, when\nenabled, its FCS before either field is accessed.","summary":"A short ERTM or streaming-mode L2CAP frame over Bluetooth makes the Linux kernel read its control field and FCS past the end of the buffer. The sources do not say whether this leads to code execution or only to information leaks or crashes.","severity":"unknown","cvss":null,"epss":null,"exploited":false,"exploited_at":null,"products":[],"ecosystems":[],"tags":["bluetooth","desktops","kernel","linux","runtime","servers"],"not_affected_if":["bluetooth-disabled"],"how_to_check":"- `uname -r` and compare against the fixed kernel builds listed in the NVD entry\n- `lsmod | grep bluetooth` to see whether the Bluetooth stack is loaded\n- unknown whether a specific config option controls exposure","fix":"- Update the Linux kernel to a release that includes the upstream commit validating L2CAP frame length; exact fixed versions: unknown\n- Unload the Bluetooth stack (`modprobe -r bluetooth`) on hosts that do not need it, as a stopgap: unknown from sources","status":"open","published_at":"2026-10-18T16:16:56+00:00","first_seen_at":"2026-10-23T21:57:15+00:00","triaged_at":"2026-10-25T05:27:19+00:00","updated_at":"2026-10-25T05:27:19+00:00","category":"runtime","confidence":0.5,"triage":{"at":"2026-10-25T05:27:19Z","model":"claude-haiku-5-5","output":{"fix":"- Update the Linux kernel to a release that includes the upstream commit validating L2CAP frame length; exact fixed versions: unknown\n- Unload the Bluetooth stack (`modprobe -r bluetooth`) on hosts that do not need it, as a stopgap: unknown from sources","reach":"network","title":"Linux kernel: short Bluetooth L2CAP frames cause out-of-bounds memory reads","impact":"medium","summary":"A short ERTM or streaming-mode L2CAP frame over Bluetooth makes the Linux kernel read its control field and FCS past the end of the buffer. The sources do not say whether this leads to code execution or only to information leaks or crashes.","category":"runtime","nicknames":[],"who_cares":["linux","kernel","bluetooth","servers","desktops"],"confidence":0.5,"needs_auth":"unknown","worst_case":"Kernel reads past buffer end; possible crash or memory disclosure","analyst_note":"Check the NVD entry and the upstream kernel commit for affected and fixed version ranges and whether ERTM is enabled by default.","how_to_check":"- `uname -r` and compare against the fixed kernel builds listed in the NVD entry\n- `lsmod | grep bluetooth` to see whether the Bluetooth stack is loaded\n- unknown whether a specific config option controls exposure","needs_analyst":true,"not_affected_if":["bluetooth-disabled"],"who_is_affected":"Systems running a Linux kernel with the Bluetooth L2CAP stack loaded, where a nearby or paired device can send ERTM or streaming-mode frames. Hosts without Bluetooth hardware or with the module disabled can skip it. The sources do not say which kernel versions are affected.","user_interaction":"no","needs_special_setup":"yes","severity_if_unknown":"unknown"},"cost_usd":0.000672,"input_tokens":3489,"output_tokens":646,"severity_before":"unknown"},"analyst_status":null,"analyst_note":null,"search":"'-2026':15A,18A '-98457':16A,19A 'access':90C,205C 'bluetooth':4A,20B,36B,81C 'bound':11A,128C 'buffer':52B,172C 'byte':99C,103C,163C 'case':137C 'caus':7A,123C 'check':149C,157C 'code':62B 'contain':191C 'control':43B,87C,104C,144C,194C 'crash':70B 'crc16':139C 'cve':14A,17A 'data':92C 'desktop':21B 'either':95C,202C 'enabl':141C,198C 'end':49B,183C 'ensur':108C 'ertm':28B,115C 'execut':63B 'fcs':46B,89C,150C,177C,200C 'fewer':160C 'field':44B,105C,145C,195C,203C 'first':107C 'follow':76C 'four':102C 'four-byt':101C 'frame':6A,34B,84C,120C,136C,186C,190C 'inform':67B 'kernel':2A,22B,40B,74C 'l2cap':5A,33B,82C,91C,148C 'lead':60B 'leak':68B 'leav':170C 'len':155C 'length':85C 'linux':1A,23B,39B,73C 'load':178C 'logic':182C 'make':37B 'memori':12A 'mode':32B,119C 'out-of-bound':8A,125C 'past':47B,180C 'present':112C 'pull':147C 'rcv':93C 'read':13A,41B,129C,179C 'remain':164C 'resolv':80C 'runtim':24B 'say':57B 'second':133C 'server':25B 'short':3A,27B,114C,135C 'short-fram':134C 'skb':154C,168C 'sourc':54B 'stream':31B,118C 'streaming-mod':30B,117C 'subsequ':176C 'subtract':151C,166C 'therefor':122C 'trim':169C 'two':98C,152C,162C 'two-byt':97C 'unchang':173C 'unpack':94C 'valid':83C,187C 'vulner':77C 'whether':58B 'without':106C,156C 'wrap':167C","nicknames":[],"mitigations":[],"who_affected":"Systems running a Linux kernel with the Bluetooth L2CAP stack loaded, where a nearby or paired device can send ERTM or streaming-mode frames. Hosts without Bluetooth hardware or with the module disabled can skip it. The sources do not say which kernel versions are affected.","tier":"C","verified":{},"analyst_revisit_at":null,"first_public_at":"2026-10-18T16:16:56+00:00","kev":null,"cvss_vector":null,"cvss_by":null,"poc_count":0,"sources":[{"source":"nvd","external_id":"CVE-2026-98457","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98457","severity":null,"published_at":"2026-10-18T16:16:56+00:00","modified_at":"2026-10-19T10:18:55+00:00","first_seen_at":"2026-10-23T21:57:15+00:00","fetched_at":"2026-10-23T22:28:56+00:00","note":null}],"documents":[],"notice":"Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai"}