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NVD / CVE Program· CNA Linux

CVE-2026-43029: mptcp: fix soft lockup in mptcp_recvmsg()

Noroxi assessment

Priority: Monitor (action score 30/100)

  • 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: 0.32% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 58b58b9ba89c43914eea90c18928e51852d10c24, 5dd8025a49c268ab6b94d978532af3ad341132a7, 6.13; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 58b58b9ba89c43914eea90c18928e51852d10c24, 5dd8025a49c268ab6b94d978532af3ad341132a7, 6.13; azl3 kernel 6.6.152.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes 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: mptcp: fix soft lockup in mptcp_recvmsg() syzbot reported a soft lockup in mptcp_recvmsg() [0]. When receiving data with MSG_PEEK | MSG_WAITALL flags, the skb is not removed from the sk_receive_queue. This causes sk_wait_data() to always find available data and never perform actual waiting, leading to a soft lockup. Fix this by adding a 'last' parameter to track the last peeked skb. This allows sk_wait_data() to make informed waiting decisions and prevent infinite loops when MSG_PEEK is used. [0]: watchdog: BUG: soft lockup - CPU#2 stuck for 156s! [server:1963] Modules linked in: CPU: 2 UID: 0 PID: 1963 Comm: server Not tainted 6.19.0-rc8 #61 PREEMPT(none) Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 RIP: 0010:sk_wait_data+0x15/0x190 Code: 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 41 56 41 55 41 54 49 89 f4 55 48 89 d5 53 48 89 fb <48> 83 ec 30 65 48 8b 05 17 a4 6b 01 48 89 44 24 28 31 c0 65 48 8b RSP: 0018:ffffc90000603ca0 EFLAGS: 00000246 RAX: 0000000000000000 RBX: ffff888102bf0800 RCX: 0000000000000001 RDX: 0000000000000000 RSI: ffffc90000603d18 RDI: ffff888102bf0800 RBP: 0000000000000000 R08: 0000000000000002 R09: 0000000000000101 R10: 0000000000000000 R11: 0000000000000075 R12: ffffc90000603d18 R13: ffff888102bf0800 R14: ffff888102bf0800 R15: 0000000000000000 FS: 00007f6e38b8c4c0(0000) GS:ffff8881b877e000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 000055aa7bff1680 CR3: 0000000105cbe000 CR4: 00000000000006f0 Call Trace: <TASK> mptcp_recvmsg+0x547/0x8c0 net/mptcp/protocol.c:2329 inet_recvmsg+0x11f/0x130 net/ipv4/af_inet.c:891 sock_recvmsg+0x94/0xc0 net/socket.c:1100 __sys_recvfrom+0xb2/0x130 net/socket.c:2256 __x64_sys_recvfrom+0x1f/0x30 net/socket.c:2267 do_syscall_64+0x59/0x2d0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x76/0x7e arch/x86/entry/entry_64.S:131 RIP: 0033:0x7f6e386a4a1d Code: 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 8d 05 f1 de 2c 00 41 89 ca 8b 00 85 c0 75 20 45 31 c9 45 31 c0 b8 2d 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 6b f3 c3 66 0f 1f 84 00 00 00 00 00 41 56 41 RSP: 002b:00007ffc3c4bb078 EFLAGS: 00000246 ORIG_RAX: 000000000000002d RAX: ffffffffffffffda RBX: 000000000000861e RCX: 00007f6e386a4a1d RDX: 00000000000003ff RSI: 00007ffc3c4bb150 RDI: 0000000000000004 RBP: 00007ffc3c4bb570 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000103 R11: 0000000000000246 R12: 00005605dbc00be0 R13: 00007ffc3c4bb650 R14: 0000000000000000 R15: 0000000000000000 </TASK>

HighCVSS 7.5 · v3.1—No exploit Fix available
Published
May 1, 2026
Updated
Aug 5, 2026
EPSS
0.3% · 26th percentile

Report tools

JSON

Action score

30

Monitor

Low priority for now.

CVSS
30 / 40 · 7.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.3%

CNA vs NVD score

NVD
—
CNA · Linux
7.5
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2026-43029

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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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.

VendorProduct
linuxlinux kernel

Affected versions

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

  • linux linux kernel6.18.1 and later · before 6.18.22
  • linux linux kernel6.19 and later · before 6.19.12
  • linux linux kernel6.12.59
  • linux linux kernel6.17.8
  • linux linux kernel6.18
  • linux linux kernel6.6.117
  • 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

    • 49888b3b457b801282b44c246d289c56e2f2a55b, 0206a9341e652167c610dcd79f3d4e9e8153984c, 7d6d10eee01edc9c20850ea75cf8273dc1170921, 6.18affected
    • 8e04ce45a8db7a080220e86e249198fa676b83dc and later · before 58b58b9ba89c43914eea90c18928e51852d10c24affected · git
    • 8e04ce45a8db7a080220e86e249198fa676b83dc and later · before de3c248d1b69eaefa2d5b3da4005936dcf590f1baffected · git
    • 8e04ce45a8db7a080220e86e249198fa676b83dc and later · before 5dd8025a49c268ab6b94d978532af3ad341132a7affected · git
    • 6.6.117 and later · before 6.7affected · semver
    • 6.12.59 and later · before 6.13affected · semver
    • 6.17.8 and later · before 6.18affected · semver
    • before 6.18not affected · semver
    • 6.18.22 and later · up to and including 6.18.*not affected · semver
    • 6.19.12 and later · up to and including 6.19.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:13linuxfrom 0—
Debian:14linuxbefore 6.19.12-16.19.12-1

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-2026-43014May 1, 2026 · net: macb: properly unregister fixed rate clocks
    22Monitor
  • ← EarlierCVE-2026-43015May 1, 2026 · net: macb: fix clk handling on PCI glue driver removal
    31Monitor
  • Later →CVE-2026-43031May 1, 2026 · net: xilinx: axienet: Fix BQL accounting for multi-BD TX packets
    30Monitor

Remediation

Which version to upgrade to

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

Product / packageFixed versionSource
Linux Linux58b58b9ba89c43914eea90c18928e51852d10c24Vendor (CNA)
Linux Linux5dd8025a49c268ab6b94d978532af3ad341132a7Vendor (CNA)
Linux Linux6.13Vendor (CNA)
Linux Linux6.18Vendor (CNA)
Linux Linux6.7Vendor (CNA)
Linux Linuxde3c248d1b69eaefa2d5b3da4005936dcf590f1bVendor (CNA)
azl3 kernel 6.6.152.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
debian:linux6.19.12-1 · Debian:14Package 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.

All national notices →

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-667 · Improper Locking

CVSS vector

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

nvd-secondary

Attack context

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

Change log

  1. Fix✗ → ✓

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

References

Show all references (2 more)

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

All records