CVE-2026-31498 (GCVE-0-2026-31498)

Vulnerability from cvelistv5 – Published: 2026-04-22 13:54 – Updated: 2026-04-22 13:54
VLAI?
Title
Bluetooth: L2CAP: Fix ERTM re-init and zero pdu_len infinite loop
Summary
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Fix ERTM re-init and zero pdu_len infinite loop l2cap_config_req() processes CONFIG_REQ for channels in BT_CONNECTED state to support L2CAP reconfiguration (e.g. MTU changes). However, since both CONF_INPUT_DONE and CONF_OUTPUT_DONE are already set from the initial configuration, the reconfiguration path falls through to l2cap_ertm_init(), which re-initializes tx_q, srej_q, srej_list, and retrans_list without freeing the previous allocations and sets chan->sdu to NULL without freeing the existing skb. This leaks all previously allocated ERTM resources. Additionally, l2cap_parse_conf_req() does not validate the minimum value of remote_mps derived from the RFC max_pdu_size option. A zero value propagates to l2cap_segment_sdu() where pdu_len becomes zero, causing the while loop to never terminate since len is never decremented, exhausting all available memory. Fix the double-init by skipping l2cap_ertm_init() and l2cap_chan_ready() when the channel is already in BT_CONNECTED state, while still allowing the reconfiguration parameters to be updated through l2cap_parse_conf_req(). Also add a pdu_len zero check in l2cap_segment_sdu() as a safeguard.
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 96298f640104e4cd9a913a6e50b0b981829b94ff , < 9760b83cfd24b38caee663f429011a0dd6064fa9 (git)
Affected: 96298f640104e4cd9a913a6e50b0b981829b94ff , < de37e2655b7abc3f59254c6b72256840f39fc6d5 (git)
Affected: 96298f640104e4cd9a913a6e50b0b981829b94ff , < e7aab23b7df89a3d754a5f0a7d2237548b328bd0 (git)
Affected: 96298f640104e4cd9a913a6e50b0b981829b94ff , < 52667c859fe33f70c2e711cb81bbd505d5eb8e75 (git)
Affected: 96298f640104e4cd9a913a6e50b0b981829b94ff , < 9a21a631ee034b1573dce14b572a24943dbfd7ae (git)
Affected: 96298f640104e4cd9a913a6e50b0b981829b94ff , < 900e4db5385ec2cacd372345a80ab9c8e105b3a3 (git)
Affected: 96298f640104e4cd9a913a6e50b0b981829b94ff , < 042e2cd4bb11e5313b19b87593616524949e4c52 (git)
Affected: 96298f640104e4cd9a913a6e50b0b981829b94ff , < 25f420a0d4cfd61d3d23ec4b9c56d9f443d91377 (git)
Affected: 4ad03ff6f680681c5f78254e37c4c856fa953629 (git)
Affected: b7d0ca715c1008acd2fc018f02a56fed88f78b75 (git)
Affected: 799263eb37a4f7f6d39334046929c3bc92452a7f (git)
Affected: 8828622fb9b4201eeb0870587052e3d834cfaf61 (git)
Affected: b432ea85ab8472763870dd0f2c186130dd36d68c (git)
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    Linux Linux Affected: 5.7
Unaffected: 0 , < 5.7 (semver)
Unaffected: 5.10.253 , ≤ 5.10.* (semver)
Unaffected: 5.15.203 , ≤ 5.15.* (semver)
Unaffected: 6.1.168 , ≤ 6.1.* (semver)
Unaffected: 6.6.131 , ≤ 6.6.* (semver)
Unaffected: 6.12.80 , ≤ 6.12.* (semver)
Unaffected: 6.18.21 , ≤ 6.18.* (semver)
Unaffected: 6.19.11 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
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      "descriptions": [
        {
          "lang": "en",
          "value": "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 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-\u003esdu 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."
        }
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        "dateUpdated": "2026-04-22T13:54:19.714Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/25f420a0d4cfd61d3d23ec4b9c56d9f443d91377"
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      "title": "Bluetooth: L2CAP: Fix ERTM re-init and zero pdu_len infinite loop",
      "x_generator": {
        "engine": "bippy-1.2.0"
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    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-31498",
    "datePublished": "2026-04-22T13:54:19.714Z",
    "dateReserved": "2026-03-09T15:48:24.103Z",
    "dateUpdated": "2026-04-22T13:54:19.714Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-31498\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-04-22T14:16:48.067\",\"lastModified\":\"2026-04-22T14:16:48.067\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"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 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-\u003esdu 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.\"}],\"metrics\":{},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/042e2cd4bb11e5313b19b87593616524949e4c52\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/25f420a0d4cfd61d3d23ec4b9c56d9f443d91377\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/52667c859fe33f70c2e711cb81bbd505d5eb8e75\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/900e4db5385ec2cacd372345a80ab9c8e105b3a3\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9760b83cfd24b38caee663f429011a0dd6064fa9\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/9a21a631ee034b1573dce14b572a24943dbfd7ae\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/de37e2655b7abc3f59254c6b72256840f39fc6d5\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/e7aab23b7df89a3d754a5f0a7d2237548b328bd0\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}"
  }
}


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  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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