NVD / CVE Program· CNA Linux

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

Noroxi assessment

Priority: Monitor (action score 28/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.11% (FIRST EPSS).
Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. Special conditions such as timing or configuration are required.
Fixed version: Linux Linux 317843d5355062020649124eb4a0d7acbcc3f53e, 3989740fa4978e1d2d51ecc62be1b01093e104ad, 3e8b25f32f2f35549d03d77da030a24a45bdef5b.
Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 317843d5355062020649124eb4a0d7acbcc3f53e, 3989740fa4978e1d2d51ecc62be1b01093e104ad, 3e8b25f32f2f35549d03d77da030a24a45bdef5b or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: atm: lec: fix use-after-free in sock_def_readable() A race condition exists between lec_atm_close() setting priv->lecd to NULL and concurrent access to priv->lecd in send_to_lecd(), lec_handle_bridge(), and lec_atm_send(). When the socket is freed via RCU while another thread is still using it, a use-after-free occurs in sock_def_readable() when accessing the socket's wait queue. The root cause is that lec_atm_close() clears priv->lecd without any synchronization, while callers dereference priv->lecd without any protection against concurrent teardown. Fix this by converting priv->lecd to an RCU-protected pointer: - Mark priv->lecd as __rcu in lec.h - Use rcu_assign_pointer() in lec_atm_close() and lecd_attach() for safe pointer assignment - Use rcu_access_pointer() for NULL checks that do not dereference the pointer in lec_start_xmit(), lec_push(), send_to_lecd() and lecd_attach() - Use rcu_read_lock/rcu_dereference/rcu_read_unlock in send_to_lecd(), lec_handle_bridge() and lec_atm_send() to safely access lecd - Use rcu_assign_pointer() followed by synchronize_rcu() in lec_atm_close() to ensure all readers have completed before proceeding. This is safe since lec_atm_close() is called from vcc_release() which holds lock_sock(), a sleeping lock. - Remove the manual sk_receive_queue drain from lec_atm_close() since vcc_destroy_socket() already drains it after lec_atm_close() returns. v2: Switch from spinlock + sock_hold/put approach to RCU to properly fix the race. The v1 spinlock approach had two issues pointed out by Eric Dumazet: 1. priv->lecd was still accessed directly after releasing the lock instead of using a local copy. 2. The spinlock did not prevent packets being queued after lec_atm_close() drains sk_receive_queue since timer and workqueue paths bypass netif_stop_queue(). Note: Syzbot patch testing was attempted but the test VM terminated unexpectedly with "Connection to localhost closed by remote host", likely due to a QEMU AHCI emulation issue unrelated to this fix. Compile testing with "make W=1 net/atm/lec.o" passes cleanly.

HighCVSS 7.0 · v3.1—No exploit Fix available

BDU:2026-07835

Published: May 1, 2026
Updated: Nov 6, 2026
EPSS: 0.1% · 1th percentile
CWE: CWE-416

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 28 / 40 · 7.0 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.1%

CISA SSVC decision

Exploitation: none
Automatable: no
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
linux	linux kernel	cpe:2.3:o:linux:linux_kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

linux linux kernel2.6.12.1 and later · before 5.10.253
linux linux kernel5.11 and later · before 5.15.203
linux linux kernel5.16 and later · before 6.1.168
linux linux kernel6.2 and later · before 6.6.134
linux linux kernel6.7 and later · before 6.12.81
linux linux kernel6.13 and later · before 6.18.22
linux linux kernel6.19 and later · before 6.19.12
linux linux kernel2.6.12
linux linux kernel7.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

Linux Linux
- 2.6.12affected
- 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 3e8b25f32f2f35549d03d77da030a24a45bdef5baffected · git
- 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 750a33f417f3d196b86375f8d9f8938bacf130feaffected · git
- 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 317843d5355062020649124eb4a0d7acbcc3f53eaffected · git
- 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before b256d055da47258e63f8b40965f276c5f23d229aaffected · git
- 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 3989740fa4978e1d2d51ecc62be1b01093e104adaffected · git
- 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before abc10f85a3965ac14b9ed7ad3e67b35604a63aa3affected · git
- 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 5fbbb1ff936d7ff9528d929c1549977e8123d8a8affected · git
- 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 and later · before 922814879542c2e397b0e9641fd36b8202a8e555affected · git
- before 2.6.12not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:12	linux	before 6.1.170-1	6.1.170-1
Debian:13	linux	before 6.12.85-1	6.12.85-1
Debian:14	linux	before 6.19.12-1	6.19.12-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
90Now
CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
89Now
CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
85Now

Published before and after this one in the same product

← EarlierCVE-2026-43048May 1, 2026 · HID: core: Mitigate potential OOB by removing bogus memset()
35Monitor
← EarlierCVE-2026-43049May 1, 2026 · HID: logitech-hidpp: Prevent use-after-free on force feedback initialisation failure
31Monitor
Later →CVE-2026-43051May 1, 2026 · HID: wacom: fix out-of-bounds read in wacom_intuos_bt_irq
32Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
Linux Linux	317843d5355062020649124eb4a0d7acbcc3f53e	Vendor (CNA)
Linux Linux	3989740fa4978e1d2d51ecc62be1b01093e104ad	Vendor (CNA)
Linux Linux	3e8b25f32f2f35549d03d77da030a24a45bdef5b	Vendor (CNA)
Linux Linux	5fbbb1ff936d7ff9528d929c1549977e8123d8a8	Vendor (CNA)
Linux Linux	750a33f417f3d196b86375f8d9f8938bacf130fe	Vendor (CNA)
Linux Linux	922814879542c2e397b0e9641fd36b8202a8e555	Vendor (CNA)
Linux Linux	abc10f85a3965ac14b9ed7ad3e67b35604a63aa3	Vendor (CNA)
Linux Linux	b256d055da47258e63f8b40965f276c5f23d229a	Vendor (CNA)
debian:linux	6.1.170-1 · Debian:12	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

TR-26-0143 · May 4, 2026(Linux Kernel Güvenlik Bildirimi)

All national notices →

Technical details

Attack conditions

Someone with local access to the system can trigger it.
A low-privileged account is enough.
No user action is required.
Special conditions such as timing or configuration are required.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Attack vector: Local
Attack complexity: High
Privileges required: Low
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-416 · Use After Free

CVSS vector

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

nvd-primary

Root cause

After a memory region is freed, another reference pointing to it is still used. By then, the same region may have been allocated for different data.

The bug in code

The whole CWE-416 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1free(dev->buf);
2/* ... another thread is still running ... */
3process(dev->buf);

Fixed

1lock(&dev->lock);
2free(dev->buf);
3dev->buf = NULL;
4unlock(&dev->lock);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

SSVC exploitation— → noneNov 6, 2026, 5:07 PM UTC
Fix✗ → ✓Sep 28, 2026, 10:09 PM UTC

For records you follow, these changes also arrive as notifications. →

References

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

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records