High

Use-after-free in Linux kernel ATM LEC sock_def_readable

IdentifiersCVE-2026-43050CWE-416· Use After Free

CVE-2026-43050 is a Linux kernel memory-safety flaw in the ATM LAN Emulation Client (LEC) subsystem. The bug is caused by a race between lec_atm_close(), which clears priv->lecd during teardown, and concurrent paths including send_to_lecd(), lec_handle_bridge(), and lec_atm_send(), which dereference priv->lecd without synchronization. If the referenced socket is freed via RCU while another thread is still using it, execution can reach sock_def_readable() and access the freed socket's wait queue, resulting in a use-after-free. The upstream fix converts priv->lecd to an RCU-protected pointer, updates assignment and dereference sites to use RCU primitives, and adds synchronize_rcu() in lec_atm_close() so teardown waits for active readers to complete.

For your environment

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation can trigger kernel use-after-free conditions in the ATM LEC networking path, leading to kernel memory corruption, denial of service via crash, and potentially confidentiality, integrity, and availability impact in kernel context. The provided context rates the issue as local, low-privilege, high-complexity, and no-user-interaction, with high C/I/A impact in SUSE scoring.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, reduce exposure by disabling or avoiding use of the ATM LEC subsystem where operationally feasible, and restrict local untrusted access because the issue is locally exploitable. Mitigation details beyond patching are otherwise not specifically provided in the available content.

Remediation

Patch, then assume compromise.

Apply a kernel update containing the upstream fix for CVE-2026-43050. The fix marks priv->lecd as an __rcu pointer, uses rcu_assign_pointer() for updates, uses rcu_access_pointer() for non-dereferencing NULL checks, wraps dereferences in rcu_read_lock()/rcu_dereference()/rcu_read_unlock(), and calls synchronize_rcu() in lec_atm_close() before teardown proceeds. Vendor advisories indicate fixed kernel packages are available for multiple SUSE product lines; install the relevant patched kernel and reboot into the updated kernel.

PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType

LinuxLinux Kerneloperating_system

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

4 sources tracked across advisories and community write-ups. News coverage will land here when it surfaces.

4 SOURCESView more in app

No news coverage yet. Advisories and community discussion only.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.

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Exposure mapping

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Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES

MITRE CVE

cve.org · CVE-2026-43050

NVD

nvd.nist.gov/vuln/detail/CVE-2026-43050

MITRE CWE · CWE-416

Use After Free

Patch

git.kernel.org/stable/c/317843d5355062020649124eb4a0d7acbcc3f53e

Patch

git.kernel.org/stable/c/3989740fa4978e1d2d51ecc62be1b01093e104ad

Patch

git.kernel.org/stable/c/3e8b25f32f2f35549d03d77da030a24a45bdef5b

Patch

git.kernel.org/stable/c/5fbbb1ff936d7ff9528d929c1549977e8123d8a8

Patch

git.kernel.org/stable/c/750a33f417f3d196b86375f8d9f8938bacf130fe

Patch

git.kernel.org/stable/c/922814879542c2e397b0e9641fd36b8202a8e555

Patch

git.kernel.org/stable/c/abc10f85a3965ac14b9ed7ad3e67b35604a63aa3

Patch

git.kernel.org/stable/c/b256d055da47258e63f8b40965f276c5f23d229a