Medium 5.5Published Apr 22, 2026

CVE-2026-31498Bluetooth: L2CAP: Fix ERTM re-init and zero pdu_len infinite loop

Updated under an hour ago (Oct 26, 2026, 10:30 PM ET)

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Exploited in the last 30 days

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.

CVSS: 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Analyzed
Record last updated: May 23, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	96298f640104e4cd9a913a6e50b0b981829b94ff builds before 9760b83cfd24b38caee663f429011a0dd6064fa9; from 96298f640104e4cd9a913a6e50b0b981829b94ff before de37e2655b7abc3f59254c6b72256840f39fc6d5; from 96298f640104e4cd9a913a6e50b0b981829b94ff before e7aab23b7df89a3d754a5f0a7d2237548b328bd0; 96298f640104e4cd9a913a6e50b0b981829b94ff builds before 52667c859fe33f70c2e711cb81bbd505d5eb8e75; 96298f640104e4cd9a913a6e50b0b981829b94ff builds before 9a21a631ee034b1573dce14b572a24943dbfd7ae; 96298f640104e4cd9a913a6e50b0b981829b94ff builds before 900e4db5385ec2cacd372345a80ab9c8e105b3a3; 96298f640104e4cd9a913a6e50b0b981829b94ff builds before 042e2cd4bb11e5313b19b87593616524949e4c52; 96298f640104e4cd9a913a6e50b0b981829b94ff builds before 25f420a0d4cfd61d3d23ec4b9c56d9f443d91377; and 10 more ranges	CNA record
linux linux_kernel linux:linux_kernel	from 4.4.238 before 4.5; from 4.9.238 before 4.10; from 4.14.200 before 4.15; from 4.19.149 before 4.20; from 5.4.69 before 5.5; from 5.7.1 before 5.10.253; from 5.11 before 5.15.203; from 5.16 before 6.1.168; and 12 more ranges	NVD

References

References

https://git.kernel.org/stable/c/9760b83cfd24b38caee663f429011a0dd6064fa9	patch
https://git.kernel.org/stable/c/de37e2655b7abc3f59254c6b72256840f39fc6d5	patch
https://git.kernel.org/stable/c/e7aab23b7df89a3d754a5f0a7d2237548b328bd0	patch
https://git.kernel.org/stable/c/52667c859fe33f70c2e711cb81bbd505d5eb8e75	patch
https://git.kernel.org/stable/c/9a21a631ee034b1573dce14b572a24943dbfd7ae	patch
https://git.kernel.org/stable/c/900e4db5385ec2cacd372345a80ab9c8e105b3a3	patch
https://git.kernel.org/stable/c/042e2cd4bb11e5313b19b87593616524949e4c52	patch
https://git.kernel.org/stable/c/25f420a0d4cfd61d3d23ec4b9c56d9f443d91377	patch

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.