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CVE-2026-64403

HIGHCVSS 7.1/10EPSS 0.27%

Last modified

CVE-2026-64403 is a high-severity vulnerability rated 7.1/10 on the CVSS scale. 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. EPSS estimates a 0.27% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1
7.1/10

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:H

EPSS Probability
0.27%

18.3th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69, < cca81b4bc672604a84f6d224a55cc77ec7dee619; >= 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69, < f70d4aa88068096f35d73e3a05eff33c0a16b9cd; >= 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69, < 7d871e969b941ce25653f7716203a0ea4d07ad4b; >= 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69, < 98d93c226bdfaa79bbdd86981921d7f106374225; >= 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69, < 996d3da39899aceb8f4910911a3f19a45a7d9d1b; >= 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69, < 73abbaf91aa33da87c008fb62c148ade561bb606; >= 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69, < 6b47bdaacfd0045687880177e0987055d8f4765a; >= 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69, < 687617555cedfb74c9e3cb85d759b908dcb17856; 78c2887130f1a7d1883195732be1b6cdab667487; ac7c597c465eb09391e40febbe088bdad601080b; ade4560e4fea198866e033fe1c02f063d6d7db2e; 99665dcf6ff803351b5e658f3a929cb498561e36; 2b59d36f22622c92c0b06aee7571f0a86a217188; 15d6538a0d6e0f6de5116081a948cba7cc3e1d3d; a556547bae00528f24b42786b41a14047db14b84; >= 3.16.66, < 3.17; >= 3.18.138, < 3.19; >= 4.4.178, < 4.5; >= 4.9.167, < 4.10; >= 4.14.110, < 4.15; >= 4.19.33, < 4.20; >= 5.0.6, < 5.1
LinuxLinux5.1

References

Timeline

Published
Last Modified
Status
Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-64403?
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.
How severe is CVE-2026-64403?
CVE-2026-64403 has a CVSS score of 7.1/10 (HIGH severity). The EPSS model estimates a 0.27% probability of exploitation in the next 30 days.
How do I fix CVE-2026-64403?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST