CVE-2026-31649Network attack vector

Remote kernel memory exposure via chain-mode underflow

Published Apr 24, 2026 · Updated Apr 24, 2026

Integer underflow in affected Linux kernel stmmac releases allows remote attackers to expose or corrupt kernel memory via network traffic. The jumbo_frm chain path subtracts a fixed buffer size from the smaller linear skb length after stmmac_xmit selects jumbo handling from the total fragmented length, wrapping the unsigned remainder and DMA-mapping out-of-bounds addresses. Exploitation requires an affected stmmac interface in nondefault chain mode and traffic that induces a large fragmented transmit buffer; IOMMU-less systems can disclose kernel memory or permit hardware memory corruption.

CVSS severity9.8
Critical
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Integer underflow in affected Linux kernel stmmac releases allows remote attackers to expose or corrupt kernel memory via network traffic. The jumbo_frm chain path subtracts a fixed buffer size from the smaller linear skb length after stmmac_xmit selects jumbo handling from the total fragmented length, wrapping the unsigned remainder and DMA-mapping out-of-bounds addresses. Exploitation requires an affected stmmac interface in nondefault chain mode and traffic that induces a large fragmented transmit buffer; IOMMU-less systems can disclose kernel memory or permit hardware memory corruption.

The record

CVE
CVE-2026-31649
Published
Apr 24, 2026
Updated
Apr 24, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-190, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 24, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 24, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=286a837217204b1ef105e3a554d0757e4fdfaac1 <10d12b9240ebf96c785f0e2e4228318cd5f3a3eb
  2. Affected versionversion=286a837217204b1ef105e3a554d0757e4fdfaac1 <275bdf762e82082f064e60a92448fa2ac43cf95b
  3. Affected versionversion=286a837217204b1ef105e3a554d0757e4fdfaac1 <2c91b39912278d0878f9ba60ba04d2518b18a08d
  4. Affected versionversion=286a837217204b1ef105e3a554d0757e4fdfaac1 <513e06735f5be575b409d195822195348b164e48
  5. Affected versionversion=286a837217204b1ef105e3a554d0757e4fdfaac1 <51f4e090b9f87b40c21b6daadb5c06e6c0a07b67
  6. Affected versionversion=286a837217204b1ef105e3a554d0757e4fdfaac1 <6fca757c20396dc2e604dcc61922264e9e3dc803
  7. Affected versionversion=286a837217204b1ef105e3a554d0757e4fdfaac1 <a2b68a9a476b9544ff31f1fbcd5d80867a8a5e2f
  8. Affected versionversion=286a837217204b1ef105e3a554d0757e4fdfaac1 <b7b8012193fd98236d7ae05d4b553f010a77b2ef
  9. Affected versionversion=3.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=286a837217204b1ef105e3a554d0757e4fdfaac1 <10d12b9240ebf96c785f0e2e4228318cd5f3a3eb; version=286a837217204b1ef105e3a554d0757e4fdfaac1 <275bdf762e82082f064e60a92448fa2ac43cf95b; version=286a837217204b1ef105e3a554d0757e4fdfaac1 <2c91b39912278d0878f9ba60ba04d2518b18a08d; version=286a837217204b1ef105e3a554d0757e4fdfaac1 <513e06735f5be575b409d195822195348b164e48; version=286a837217204b1ef105e3a554d0757e4fdfaac1 <51f4e090b9f87b40c21b6daadb5c06e6c0a07b67; version=286a837217204b1ef105e3a554d0757e4fdfaac1 <6fca757c20396dc2e604dcc61922264e9e3dc803; version=286a837217204b1ef105e3a554d0757e4fdfaac1 <a2b68a9a476b9544ff31f1fbcd5d80867a8a5e2f; version=286a837217204b1ef105e3a554d0757e4fdfaac1 <b7b8012193fd98236d7ae05d4b553f010a77b2ef; version=3.2

Published CVSS scores

9.8kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-190Integer Overflow or Wraparound
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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