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

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.

Timeline

Scores

EPSS (exploitation in 30 days)

0.27% · top 81% of all CVEs (12 Nov 2026)

CISA SSVC

Exploitation: none · Automatable: no · Technical impact: partial

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.1.

Affected products

• Linux · Linux

  • affected 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 – < cca81b4bc672604a84f6d224a55cc77ec7dee619
  • affected 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 – < f70d4aa88068096f35d73e3a05eff33c0a16b9cd
  • affected 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 – < 7d871e969b941ce25653f7716203a0ea4d07ad4b
  • affected 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 – < 98d93c226bdfaa79bbdd86981921d7f106374225
  • affected 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 – < 996d3da39899aceb8f4910911a3f19a45a7d9d1b
  • affected 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 – < 73abbaf91aa33da87c008fb62c148ade561bb606
  • affected 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 – < 6b47bdaacfd0045687880177e0987055d8f4765a
  • affected 7c9cbd0b5e38a1672fcd137894ace3b042dfbf69 – < 687617555cedfb74c9e3cb85d759b908dcb17856
  • affected 78c2887130f1a7d1883195732be1b6cdab667487
  • affected ac7c597c465eb09391e40febbe088bdad601080b
  • affected ade4560e4fea198866e033fe1c02f063d6d7db2e
  • affected 99665dcf6ff803351b5e658f3a929cb498561e36
  • affected 2b59d36f22622c92c0b06aee7571f0a86a217188
  • affected 15d6538a0d6e0f6de5116081a948cba7cc3e1d3d
  • affected a556547bae00528f24b42786b41a14047db14b84
  • affected 3.16.66 – < 3.17
  • affected 3.18.138 – < 3.19
  • affected 4.4.178 – < 4.5
  • affected 4.9.167 – < 4.10
  • affected 4.14.110 – < 4.15
  • affected 4.19.33 – < 4.20
  • affected 5.0.6 – < 5.1

• Linux · Linux

  • affected 5.1
  • unaffected < 5.1
  • unaffected 5.10.261 – ≤ 5.10.*
  • unaffected 5.15.212 – ≤ 5.15.*
  • unaffected 6.1.178 – ≤ 6.1.*
  • unaffected 6.6.145 – ≤ 6.6.*
  • unaffected 6.12.96 – ≤ 6.12.*
  • unaffected 6.18.39 – ≤ 6.18.*
  • unaffected 7.1.4 – ≤ 7.1.*
  • unaffected 7.2 – ≤ *

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• EUVD EUVD-2026-48947 (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-64403](https://cveledger.app/badge/CVE-2026-64403.svg)](https://cveledger.app/cve/CVE-2026-64403)

Record last updated 19 Oct 2026, 20:38 UTC.