{"id":"CVE-2026-31498","title":"Bluetooth: L2CAP: Fix ERTM re-init and zero pdu_len infinite loop","summary":"In the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: Fix ERTM re-init and zero pdu_len infinite loop\n\nl2cap_config_req() processes CONFIG_REQ for channels in BT_CONNECTED\nstate to support L2CAP reconfigu…","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= 96298f640104e4cd9a913a6e50b0b981829b94ff < 9760b83cfd24b38caee663f429011a0dd6064fa9","Linux >= 96298f640104e4cd9a913a6e50b0b981829b94ff < de37e2655b7abc3f59254c6b72256840f39fc6d5","Linux >= 96298f640104e4cd9a913a6e50b0b981829b94ff < e7aab23b7df89a3d754a5f0a7d2237548b328bd0","Linux >= 96298f640104e4cd9a913a6e50b0b981829b94ff < 52667c859fe33f70c2e711cb81bbd505d5eb8e75","Linux >= 96298f640104e4cd9a913a6e50b0b981829b94ff < 9a21a631ee034b1573dce14b572a24943dbfd7ae","Linux >= 96298f640104e4cd9a913a6e50b0b981829b94ff < 900e4db5385ec2cacd372345a80ab9c8e105b3a3","Linux >= 96298f640104e4cd9a913a6e50b0b981829b94ff < 042e2cd4bb11e5313b19b87593616524949e4c52","Linux >= 96298f640104e4cd9a913a6e50b0b981829b94ff < 25f420a0d4cfd61d3d23ec4b9c56d9f443d91377","Linux 4ad03ff6f680681c5f78254e37c4c856fa953629","Linux b7d0ca715c1008acd2fc018f02a56fed88f78b75","Linux 799263eb37a4f7f6d39334046929c3bc92452a7f","Linux 8828622fb9b4201eeb0870587052e3d834cfaf61","Linux b432ea85ab8472763870dd0f2c186130dd36d68c","Linux >= 4.4.238 < 4.5","Linux >= 4.9.238 < 4.10","Linux >= 4.14.200 < 4.15","Linux >= 4.19.149 < 4.20","Linux >= 5.4.69 < 5.5","Linux 5.7"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-05T21:35:45.390526Z"},"published":"2026-04-22","updated":"2026-11-05","sourceUpdated":"2026-11-05T21:45:03.103Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-31498","references":[{"url":"https://git.kernel.org/stable/c/9760b83cfd24b38caee663f429011a0dd6064fa9"},{"url":"https://git.kernel.org/stable/c/de37e2655b7abc3f59254c6b72256840f39fc6d5"},{"url":"https://git.kernel.org/stable/c/e7aab23b7df89a3d754a5f0a7d2237548b328bd0"},{"url":"https://git.kernel.org/stable/c/52667c859fe33f70c2e711cb81bbd505d5eb8e75"},{"url":"https://git.kernel.org/stable/c/9a21a631ee034b1573dce14b572a24943dbfd7ae"},{"url":"https://git.kernel.org/stable/c/900e4db5385ec2cacd372345a80ab9c8e105b3a3"},{"url":"https://git.kernel.org/stable/c/042e2cd4bb11e5313b19b87593616524949e4c52"},{"url":"https://git.kernel.org/stable/c/25f420a0d4cfd61d3d23ec4b9c56d9f443d91377"}],"tags":["cve.org"],"epss":0.00123,"epssPercentile":0.02054,"ingestedAt":"2026-11-05T23:41:31.985Z","slug":"CVE-2026-31498","body":"## Overview\n\nIn the Linux kernel, the following vulnerability has been resolved:\n\nBluetooth: L2CAP: Fix ERTM re-init and zero pdu_len infinite loop\n\nl2cap_config_req() processes CONFIG_REQ for channels in BT_CONNECTED\nstate to support L2CAP reconfiguration (e.g. MTU changes). However,\nsince both CONF_INPUT_DONE and CONF_OUTPUT_DONE are already set from\nthe initial configuration, the reconfiguration path falls through to\nl2cap_ertm_init(), which re-initializes tx_q, srej_q, srej_list, and\nretrans_list without freeing the previous allocations and sets\nchan->sdu to NULL without freeing the existing skb. This leaks all\npreviously allocated ERTM resources.\n\nAdditionally, l2cap_parse_conf_req() does not validate the minimum\nvalue of remote_mps derived from the RFC max_pdu_size option. A zero\nvalue propagates to l2cap_segment_sdu() where pdu_len becomes zero,\ncausing the while loop to never terminate since len is never\ndecremented, exhausting all available memory.\n\nFix the double-init by skipping l2cap_ertm_init() and\nl2cap_chan_ready() when the channel is already in BT_CONNECTED state,\nwhile still allowing the reconfiguration parameters to be updated\nthrough l2cap_parse_conf_req(). Also add a pdu_len zero check in\nl2cap_segment_sdu() as a safeguard.\n\n## Affected\n\n- `Linux >= 96298f640104e4cd9a913a6e50b0b981829b94ff < 9760b83cfd24b38caee663f429011a0dd6064fa9`\n- `Linux >= 96298f640104e4cd9a913a6e50b0b981829b94ff < de37e2655b7abc3f59254c6b72256840f39fc6d5`\n- `Linux >= 96298f640104e4cd9a913a6e50b0b981829b94ff < e7aab23b7df89a3d754a5f0a7d2237548b328bd0`\n- `Linux >= 96298f640104e4cd9a913a6e50b0b981829b94ff < 52667c859fe33f70c2e711cb81bbd505d5eb8e75`\n- `Linux >= 96298f640104e4cd9a913a6e50b0b981829b94ff < 9a21a631ee034b1573dce14b572a24943dbfd7ae`\n- `Linux >= 96298f640104e4cd9a913a6e50b0b981829b94ff < 900e4db5385ec2cacd372345a80ab9c8e105b3a3`\n- `Linux >= 96298f640104e4cd9a913a6e50b0b981829b94ff < 042e2cd4bb11e5313b19b87593616524949e4c52`\n- `Linux >= 96298f640104e4cd9a913a6e50b0b981829b94ff < 25f420a0d4cfd61d3d23ec4b9c56d9f443d91377`\n- `Linux 4ad03ff6f680681c5f78254e37c4c856fa953629`\n- `Linux b7d0ca715c1008acd2fc018f02a56fed88f78b75`\n- `Linux 799263eb37a4f7f6d39334046929c3bc92452a7f`\n- `Linux 8828622fb9b4201eeb0870587052e3d834cfaf61`\n- `Linux b432ea85ab8472763870dd0f2c186130dd36d68c`\n- `Linux >= 4.4.238 < 4.5`\n- `Linux >= 4.9.238 < 4.10`\n- `Linux >= 4.14.200 < 4.15`\n- `Linux >= 4.19.149 < 4.20`\n- `Linux >= 5.4.69 < 5.5`\n- `Linux 5.7`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}