VulnerabilityPublished 1 May 2026Updated 6 Nov 2026

CVE-2026-43050: Linux kernel · atm: lec: fix use-after-free in sock_def_readable()

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in b256d055da47258e63f8b40965f276c5f23d229a : patch Linux kernel soon.

Data as of 6 Nov 2026, 16:20 UTC

Severity

High

Rated High by Threat Radar's AI analysis · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-06.

Patch

Available – fixed in b256d055da47258e63f8b40965f276c5f23d229a, abc10f85a3965ac14b9ed7ad3e67b35604a63aa3, 922814879542c2e397b0e9641fd36b8202a8e555 +5

Exploitation evidence

Disclosed: evidence found.
CVE published 1 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 6 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < b256d055da47258e63f8b40965f276c5f23d229a	Fixed in b256d055da47258e63f8b40965f276c5f23d229a
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < abc10f85a3965ac14b9ed7ad3e67b35604a63aa3	Fixed in abc10f85a3965ac14b9ed7ad3e67b35604a63aa3
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 922814879542c2e397b0e9641fd36b8202a8e555	Fixed in 922814879542c2e397b0e9641fd36b8202a8e555
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 3989740fa4978e1d2d51ecc62be1b01093e104ad	Fixed in 3989740fa4978e1d2d51ecc62be1b01093e104ad
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 317843d5355062020649124eb4a0d7acbcc3f53e	Fixed in 317843d5355062020649124eb4a0d7acbcc3f53e
LinuxLinux	Affected ≥ 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2, < 750a33f417f3d196b86375f8d9f8938bacf130fe	Fixed in 750a33f417f3d196b86375f8d9f8938bacf130fe

AI-suggested

A fix is available and has been applied in the Linux kernel commits listed as fixedVersions. Users should update their Linux kernel to a version including these fixes. No additional mitigation is required beyond applying the official patch.

Description

A use-after-free vulnerability in the Linux kernel's ATM LEC (Logical Link Control) module was fixed. The flaw arises from a race condition where a socket pointer is cleared without synchronization while other threads may still access it, leading to unsafe memory access in sock_def_readable(). The fix involves converting the pointer to an RCU-protected pointer and applying proper synchronization to prevent concurrent access after free.

Impact

The vulnerability allows a use-after-free condition in the kernel's ATM LEC socket handling, which can cause kernel memory corruption or crashes. This could potentially be exploited to cause denial of service or escalate privileges if an attacker can trigger the race condition. However, no known exploits in the wild have been reported.

Summary

CVE-2026-43050 addresses a use-after-free vulnerability in the Linux kernel ATM LEC subsystem. The root cause is a race condition between lec_atm_close() clearing the priv->lecd pointer without synchronization and concurrent access to this pointer in functions like send_to_lecd(), lec_handle_bridge(), and lec_atm_send(). This leads to use-after-free when the socket is freed via RCU but still accessed. The fix converts priv->lecd to an RCU-protected pointer, uses rcu_assign_pointer() and rcu_access_pointer() for safe pointer assignments and checks, and applies rcu_read_lock and synchronize_rcu() to ensure safe concurrent access and teardown. The patch replaces a previous spinlock approach that was insufficient to prevent the race. The fix is included in several Linux kernel commits identified by their hashes.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 6 Nov 2026, 16:20 UTC

Technical details

References

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