CVE Intelligence
Medium Denial of service

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

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.

Published Apr 22, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: Linux

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.2% (30-day exploitation probability)+1
  • Technical severity (medium)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.16%
ahead of 5% of scored CVEs · Oct 14, 2026
Affects
Linux
Linux and 1 more
CVSS base
5.5
Medium · 1 source(s)

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)
  • Documented patch — git.kernel.org (NIST National Vulnerability Database)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Linux Linux, Linux Linux Kernel).
  2. Apply the fixed version or the patch documented under Remediation.
  3. Search available logs for exploit probes matching the vulnerability class (denial of service), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Linux Linux version b7d0ca715c1008acd2fc018f02a56fed88f78b75≥ 96298f640104e4cd9a913a6e50b0b981829b94ff and < 9760b83cfd24b38caee663f429011a0dd6064fa9≥ 96298f640104e4cd9a913a6e50b0b981829b94ff and < de37e2655b7abc3f59254c6b72256840f39fc6d5≥ 96298f640104e4cd9a913a6e50b0b981829b94ff and < e7aab23b7df89a3d754a5f0a7d2237548b328bd0≥ 96298f640104e4cd9a913a6e50b0b981829b94ff and < 52667c859fe33f70c2e711cb81bbd505d5eb8e75≥ 96298f640104e4cd9a913a6e50b0b981829b94ff and < 9a21a631ee034b1573dce14b572a24943dbfd7ae≥ 96298f640104e4cd9a913a6e50b0b981829b94ff and < 900e4db5385ec2cacd372345a80ab9c8e105b3a3≥ 96298f640104e4cd9a913a6e50b0b981829b94ff and < 042e2cd4bb11e5313b19b87593616524949e4c52
and 11 more ≥ 96298f640104e4cd9a913a6e50b0b981829b94ff and < 25f420a0d4cfd61d3d23ec4b9c56d9f443d91377version 4ad03ff6f680681c5f78254e37c4c856fa953629version 799263eb37a4f7f6d39334046929c3bc92452a7fversion 8828622fb9b4201eeb0870587052e3d834cfaf61version b432ea85ab8472763870dd0f2c186130dd36d68c≥ 4.4.238 and < 4.5≥ 4.9.238 and < 4.10≥ 4.14.200 and < 4.15≥ 4.19.149 and < 4.20≥ 5.4.69 and < 5.5version 5.7
Vulnerable CVE Program (cve.org) e CISA ADP
Linux Linux Kernel version 7.0-rc7≥ 6.13 and < 6.18.21≥ 4.9.238 and < 4.10≥ 4.14.200 and < 4.15≥ 4.19.149 and < 4.20≥ 5.4.69 and < 5.5≥ 5.7.1 and < 5.10.253≥ 5.11 and < 5.15.203
and 12 more ≥ 5.16 and < 6.1.168≥ 6.2 and < 6.6.131≥ 6.7 and < 6.12.80≥ 4.4.238 and < 4.5≥ 6.19 and < 6.19.11version 5.7version 7.0-rc1version 7.0-rc2version 7.0-rc3version 7.0-rc4version 7.0-rc5version 7.0-rc6
Vulnerable NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
5.5 CVSS 3.1 Medium 1.8 3.6 nvd@nist.gov via NIST National Vulnerability Database
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-835 · Infinite Loop

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.16%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
  • Track CPU/memory spikes and availability drops correlated with request patterns.
endpoint telemetry (EDR)resource metrics

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · linux/linux
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • Fix documented
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVSS changed · 5.5
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Analyzed
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVE published
    Apr 22, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

8 on the record

Elsewhere on this site

Linux
every CVE for this vendor
Denial of service
same class
CWE-835
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-99999 ipv4: validate checksum_start before completing checksum 12h
  • CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 12h
  • CVE-2026-98424 wifi: cfg80211: undo netns switch if renaming the wiphy fails 1d
  • CVE-2026-98425 wifi: mac80211: don't warn when an IBSS has no channel to scan 1d
  • CVE-2026-98426 wifi: mwifiex: fix IRQ leak using wrong index in MSI-X error path 1d
  • CVE-2026-98427 net/sched: codel: bound the dropping loop per dequeue call 1d

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No CISA SSVC assessment.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-31498 is "Bluetooth: L2CAP: Fix ERTM re-init and zero pdu_len infinite loop", rated Medium. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.5 describes technical severity. EPSS 0.16% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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