High Memory corruption

CVE-2026-64403 — Bluetooth: L2CAP: validate option length before reading conf opt value

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: validate option length before reading conf opt value l2cap_get_conf_opt() derives the option length from the attacker-controlled opt->len field and immediately dereferences opt->val (as u8, get_unaligned_le16() or get_unaligned_le32(), or a raw pointer for the default case) before any caller has confirmed that opt->len bytes are present in the buffer. The callers (l2cap_parse_conf_req(), l2cap_parse_conf_rsp() and l2cap_conf_rfc_get()) only detect a malformed option afterwards, once the running length has gone negative, by which point the out-of-bounds read has already executed. An existing post-hoc length check keeps the garbage value from being consumed, so this is not a data leak in the current control flow. It is still a validate-after-use ordering bug: up to 4 bytes are read past the end of the buffer before it is known to contain them, and it is fragile to future changes in the callers. Fix it at the source. Pass the end of the buffer into l2cap_get_conf_opt() and refuse to touch opt->val unless the full option (header + value) fits. Each caller computes an end pointer once before the loop and checks the return value directly instead of inferring the error from a negative length.

Published Jul 25, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: Linux

Low

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

Technical severity (high)+6

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

—

No EPSS score.

Affects

Linux

Linux and 1 more

CVSS base

7.1

High · 2 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.

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

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Linux	Linux	version a556547bae00528f24b42786b41a14047db14b84≥ 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 and < 73abbaf91aa33da87c008fb62c148ade561bb606≥ 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 and < 6b47bdaacfd0045687880177e0987055d8f4765a≥ 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 and < 687617555cedfb74c9e3cb85d759b908dcb17856version 78c2887130f1a7d1883195732be1b6cdab667487version ac7c597c465eb09391e40febbe088bdad601080bversion ade4560e4fea198866e033fe1c02f063d6d7db2eversion 99665dcf6ff803351b5e658f3a929cb498561e36 and 15 more version 2b59d36f22622c92c0b06aee7571f0a86a217188version 15d6538a0d6e0f6de5116081a948cba7cc3e1d3d≥ 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 and < 996d3da39899aceb8f4910911a3f19a45a7d9d1b≥ 3.16.66 and < 3.17≥ 3.18.138 and < 3.19≥ 4.4.178 and < 4.5≥ 4.9.167 and < 4.10≥ 4.14.110 and < 4.15≥ 4.19.33 and < 4.20≥ 5.0.6 and < 5.1version 5.1≥ 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 and < 98d93c226bdfaa79bbdd86981921d7f106374225≥ 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 and < 7d871e969b941ce25653f7716203a0ea4d07ad4b≥ 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 and < f70d4aa88068096f35d73e3a05eff33c0a16b9cd≥ 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 and < cca81b4bc672604a84f6d224a55cc77ec7dee619	Vulnerable	CVE Program (cve.org) e CISA ADP
Linux	Linux Kernel	≥ 3.18.138 and < 3.19≥ 3.16.66 and < 3.17≥ 4.4.178 and < 4.5≥ 4.9.167 and < 4.10≥ 4.14.110 and < 4.15≥ 4.19.33 and < 4.20≥ 5.0.6 and < 5.10.261≥ 5.11 and < 5.15.212 and 7 more ≥ 5.16 and < 6.1.178≥ 6.2 and < 6.6.145≥ 6.7 and < 6.12.96≥ 6.13 and < 6.18.39≥ 6.19 and < 7.1.4version 7.2-rc1version 7.2-rc2	Vulnerable	NIST National Vulnerability Database

Attack characteristics

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

Attack vector

Adjacent

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

High

Every base score collected

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

Score	Version	Severity	Expl.	Impact	Scored by
7.1	CVSS 3.1	High	2.8	4.2	416baaa9-dc9f-4396-8d5f-8c081fb06d67 via NIST National Vulnerability Database
7.1	CVSS 3.1	High	—	—	Linux via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H (score shown at the top: 416baaa9-dc9f-4396-8d5f-8c081fb06d67)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-476 · NULL Pointer Dereference

Other CVEs with this weakness →

Detection

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

Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.

endpoint telemetry (EDR)crash dumps

Timeline

What happened to this CVE, newest first.

2026
Affected products added · linux/linux
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 15, 2026
Fix documented
Oct 15, 2026 · NIST National Vulnerability Database
CVSS changed · 7.1
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Jul 25, 2026 · Linux

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

8 on the record

git.kernel.org/stable/c/98d93c226bdfaa79bbdd86981921d7f106374225
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/f70d4aa88068096f35d73e3a05eff33c0a16b9cd
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/6b47bdaacfd0045687880177e0987055d8f4765a
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/687617555cedfb74c9e3cb85d759b908dcb17856
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/996d3da39899aceb8f4910911a3f19a45a7d9d1b
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/cca81b4bc672604a84f6d224a55cc77ec7dee619
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/7d871e969b941ce25653f7716203a0ea4d07ad4b
Patch, NIST National Vulnerability Database
git.kernel.org/stable/c/73abbaf91aa33da87c008fb62c148ade561bb606
Patch, NIST National Vulnerability Database

Elsewhere on this site

Linux
every CVE for this vendor

Memory corruption
same class

CWE-476
other pages naming this weakness

Related CVEs (same products)

Critical CVE-2026-99999 ipv4: validate checksum_start before completing checksum 13h
Unknown CVE-2026-98432 ipv4: free inet_opt and ireq_opt after an RCU grace period 13h
Unknown CVE-2026-98424 wifi: cfg80211: undo netns switch if renaming the wiphy fails 1d
Unknown CVE-2026-98425 wifi: mac80211: don't warn when an IBSS has no channel to scan 1d
Unknown CVE-2026-98426 wifi: mwifiex: fix IRQ leak using wrong index in MSI-X error path 1d
Unknown 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 FIRST EPSS score.
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-2026-64403 is "Bluetooth: L2CAP: validate option length before reading conf opt value", rated High. It affects Linux (Linux); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.1 describes technical severity. 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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