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CVE Record

CVE-2022-48906: mptcp: Correctly set DATA_FIN timeout when number of retransmits is large

In the Linux kernel, the following vulnerability has been resolved: mptcp: Correctly set DATA_FIN timeout when number of retransmits is large Syzkaller with UBSAN uncovered a scenario where a large number of DATA_FIN retransmits caused a shift-out-of-bounds in the DATA_FIN timeout calculation: ================================================================================ UBSAN: shift-out-of-bounds in net/mptcp/protocol.c:470:29 shift exponent 32 is too large for 32-bit type 'unsigned int' CPU: 1 PID: 13059 Comm: kworker/1:0 Not tainted 5.17.0-rc2-00630-g5fbf21c90c60 #1 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014 Workqueue: events mptcp_worker Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 ubsan_epilogue+0xb/0x5a lib/ubsan.c:151 __ubsan_handle_shift_out_of_bounds.cold+0xb2/0x20e lib/ubsan.c:330 mptcp_set_datafin_timeout net/mptcp/protocol.c:470 [inline] __mptcp_retrans.cold+0x72/0x77 net/mptcp/protocol.c:2445 mptcp_worker+0x58a/0xa70 net/mptcp/protocol.c:2528 process_one_work+0x9df/0x16d0 kernel/workqueue.c:2307 worker_thread+0x95/0xe10 kernel/workqueue.c:2454 kthread+0x2f4/0x3b0 kernel/kthread.c:377 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295 </TASK> ================================================================================ This change limits the maximum timeout by limiting the size of the shift, which keeps all intermediate values in-bounds.

UnknownCVSS not scoredNot KEV-listedUpdated
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Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

CVE-2022-48906 is a Linux kernel MPTCP bug where repeated DATA_FIN retransmissions can make a timeout calculation invalid. Public sources describe a kernel undefined-behavior finding, not confirmed real-world compromise. Business urgency depends on whether affected kernels run MPTCP-enabled workloads.

Executive priority

Prioritize normal kernel patch management, with higher urgency for internet-facing or network-heavy Linux systems using MPTCP. There is no cited evidence of exploitation, but kernel flaws can have operational impact and should not be left indefinitely unpatched.

Technical view

The Linux kernel MPTCP code calculated DATA_FIN timeout using a left shift that could exceed the width of an unsigned int when retransmit counts became large. Syzkaller with UBSAN found the shift-out-of-bounds condition in net/mptcp/protocol.c. The fix limits the shift size so intermediate values stay in bounds.

Likely exposure

Exposure is most relevant to systems running affected Linux kernel versions with MPTCP available or in use. The CVE record lists Linux kernel versions including 5.13, 5.15.27, 5.16.13, and 5.17 as affected, but distro backports may change practical exposure.

Exploitation context

The source bundle does not show active exploitation, and CISA KEV status is false. Evidence comes from Syzkaller/UBSAN testing. Public sources do not state a complete attacker model, exploitability, or impact beyond the kernel undefined-behavior condition.

Researcher notes

Public details identify the vulnerable area as MPTCP DATA_FIN timeout handling in net/mptcp/protocol.c. The fix constrains timeout growth by limiting shift size. Sources do not provide CVSS, CWE, exploit status, or a vendor-neutral impact statement.

Mitigation direction

  • Update to a vendor-supported kernel containing the referenced upstream stable fixes.
  • Check Linux distribution advisories for backported fixes before relying on upstream version numbers.
  • If MPTCP is not required, review vendor guidance on disabling or limiting its use.

Validation and detection

  • Inventory Linux kernel versions across servers, appliances, containers hosts, and network systems.
  • Determine whether MPTCP is compiled, enabled, or used on affected systems.
  • Confirm the relevant stable fix commit or distro backport is present.
  • Review kernel logs for MPTCP-related warnings or UBSAN reports where available.
Prepared
Confidence
medium
Sources
5

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
1ADP providers
4Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux6477dd39e62c3a67cfa368ddc127410b4ae424c6, 6477dd39e62c3a67cfa368ddc127410b4ae424c6, 6477dd39e62c3a67cfa368ddc127410b4ae424c6, 0af76111c2a6326e4bb56f64a6e453c6ec6dd2daunaffected
LinuxLinux5.13, 0, 5.15.27, 5.16.13, 5.17affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.