CVE-2026-31498: linux Infinite Loop

Vulnerability summary

CVE-2026-31498 is a medium (CVSS 5.5) Infinite Loop vulnerability in linux. EPSS estimates a 0.16% chance of exploitation in the next 30 days, higher than 5.1% of scored vulnerabilities.

Timeline

1. 22-04-2026
   PublishedVulnerability first disclosed.
2. 23-05-2026
   Last modifiedVulnerability information updated.

Description

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.

• CWE-835Loop with Unreachable Exit Condition ('Infinite Loop')The product contains an iteration or loop with an exit condition that cannot be reached, i.e., an infinite loop.