Bluetooth: L2CAP: refuse __l2cap_chan_add if chan already has conn
Affects the Linux kernel Bluetooth L2CAP code in the 5.10, 5.15, 6.1, 6.6, 6.12, 6.18 and 7.1 stable branches before their fixed releases; fixed in the listed point releases and in 7.2.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, and 2 more
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. A time-of-check/time-of-use race between l2cap_chan_connect and l2cap_sock_bind can violate the invariant that an l2cap_chan is linked to an l2cap_conn at most once.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 33/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Fix
- Fixed in 5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, and 2 more
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: refuse __l2cap_chan_add if chan already has conn l2cap_chan may be linked to l2cap_conn at most once. This is assumed in several places, eg l2cap_chan_del cleanup. There is a TOCTOU race where the invariant is violated: [Task 1] [Task 2] l2cap_chan_connect l2cap_sock_bind l2cap_chan_lock lock_sock l2cap_state_change if (sk->sk_state != BT_OPEN) chan->state = BT_CONNECT l2cap_sock_state_change_cb chan->state = BT_BOUND sk->sk_state = BT_BOUND lock_sock <------------------ release_sock sk->sk_state = BT_CONNECT l2cap_sock_connect() does not check sk->sk_state, so since chan->state is now BT_BOUND, subsequent connect() ends up with second __l2cap_chan_add. Explicitly document and check the invariant in __l2cap_chan_add with WARN_ON_ONCE. The only callsite where it could be hit is l2cap_chan_connect, so add pre-check there to avoid relying on chan->state. chan->state read/write is not properly guarded currently so there can be other TOCTOUC problems. Add l2cap_lock_chan in l2cap_sock_bind() to guard chan->state write.
What to do
Check whether your setup matches what the bug needs.
A time-of-check/time-of-use race between l2cap_chan_connect and l2cap_sock_bind can violate the invariant that an l2cap_chan is linked to an l2cap_conn at most once.Upgrade to a fixed version: 5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, or one of 2 more.
Timeline
- CVE published
- First seen by cve.now
- Posted on X by cve.now
Affected versions
- Linux Linux
From 5.10.265 · fixed in 5.10.273; From 5.15.216 · fixed in 5.15.224; From 6.1.183 · fixed in 6.1.191; From 6.6.145 · fixed in 6.6.161; From 6.12.97 · fixed in 6.12.115; From 6.18.39 · fixed in 6.18.60; From 7.1.4 · fixed in 7.2
- Linux Linux
7.2
Evidence 8
- Link
- Link
- Link
- Link
- Link
Corrections
None so far.
Something wrong on this page? Report an error. Every fix is listed here.
Questions about CVE-2026-99239
What does this mean?
A race between l2cap_chan_connect and l2cap_sock_bind can link an L2CAP channel to a connection more than once, breaking the rule that each channel is linked at most once. The fix makes __l2cap_chan_add refuse to add a channel that already has a connection.Source: git.kernel.org
Am I affected, and how do I check?
Affected kernels are those from 5.10.265 to before 5.10.273, 5.15.216 to before 5.15.224, 6.1.183 to before 6.1.191, 6.6.145 to before 6.6.161, 6.12.97 to before 6.12.115, 6.18.39 to before 6.18.60, and 7.1.4 to before 7.2. Check the running kernel with uname -r and see whether the Bluetooth L2CAP code is in use.Source: git.kernel.org
What should I do about it?
Update to the fixed release for the branch in use: 5.10.273, 5.15.224, 6.1.191, 6.6.161, 6.12.115, 6.18.60, or 7.2. Use the stable kernel release for the matching branch.Source: git.kernel.org
Is it being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data