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CVE Record

CVE-2024-26828: cifs: fix underflow in parse_server_interfaces()

In the Linux kernel, the following vulnerability has been resolved: cifs: fix underflow in parse_server_interfaces() In this loop, we step through the buffer and after each item we check if the size_left is greater than the minimum size we need. However, the problem is that "bytes_left" is type ssize_t while sizeof() is type size_t. That means that because of type promotion, the comparison is done as an unsigned and if we have negative bytes left the loop continues instead of ending.

CriticalCVSS 9.4Not KEV-listedUpdated
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Glexia's TakeAutomated analysiscritical

Security readout for executives and security teams

Plain-English summary

A flaw in Linux CIFS file-sharing code can mishandle malformed server-interface data. A negative remaining-length value may be treated as a large unsigned number, causing parsing to continue beyond its intended boundary. The supplied CVSS score is 9.4, indicating potentially serious confidentiality, integrity, and availability impact.

Executive priority

Treat this as an urgent kernel remediation item for CIFS-using systems because the supplied severity is critical. Prioritize exposed or business-critical file-sharing workloads, but avoid claiming an active attack campaign. Require vendor-confirmed package status and evidence that updated kernels are actually running.

Technical view

In parse_server_interfaces(), signed ssize_t bytes_left is compared with unsigned sizeof() values. Integer promotion converts the comparison to unsigned, so a negative remaining length may satisfy the loop condition. This permits continued buffer parsing after the calculated data is exhausted, creating an underflow and potential out-of-bounds processing condition.

Likely exposure

Exposure is concentrated in hosts running affected Linux kernels where CIFS functionality processes server-interface data. The bundle's version representation is ambiguous and does not establish reliable distribution-specific package boundaries. Confirm exposure using vendor advisories and package changelogs rather than relying solely on the listed versions.

Exploitation context

The network-based CVSS vector describes low-complexity, unauthenticated exploitation without user interaction. However, the supplied sources do not document a public exploit or confirmed exploitation, and the CVE is not listed as KEV. Do not treat active exploitation as established.

Researcher notes

The core defect is signed-to-unsigned conversion in a remaining-buffer-length check. The cited kernel commits document stable-tree corrections. The bundle does not provide sufficient evidence to assert code execution, a working exploit, active exploitation, or precise distribution package boundaries.

Mitigation direction

  • Install a vendor-supported kernel containing the applicable stable fix.
  • Check Linux distribution advisories for corrected package versions and reboot requirements.
  • Prioritize systems using CIFS or SMB file-sharing functionality.
  • Restrict unnecessary connectivity to untrusted SMB servers while remediation is pending.

Validation and detection

  • Inventory kernel versions and installed kernel packages across Linux hosts.
  • Identify hosts using CIFS modules, mounts, or SMB-dependent workloads.
  • Compare package changelogs with CVE-2024-26828 and the cited stable commits.
  • After updating, verify the corrected kernel is running following any required reboot.
Prepared
Confidence
high
Sources
6

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

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

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CVE-2024-26828 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

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Vulnerability profileCVE Program record
Severity
Critical
CVSS
9.4 (3.1)
Known Exploited
No
Published

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

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.

2CVSS vectors
3Timeline events
2ADP providers
5Source links

SSVC decision data

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

CVSS vector scores

2 official scores

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
9.4CVSS 3.1CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:H3.95.5Linux
6.7CVSS 3.1MediumCVSS:3.1/AV:A/AC:L/PR:L/UI:R/S:U/C:N/I:H/A:H1.55.2CISA-ADP

Vulnerability scoring details

Base CVSS 3.1 score

9.4Critical
CVSS 3.1 vector shape for CVE-2024-26828Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

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
cvssV3_1other:ssvc
CVECVE Program Container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxfe856be475f7cf5ffcde57341d175ce9fd09434b, fe856be475f7cf5ffcde57341d175ce9fd09434b, fe856be475f7cf5ffcde57341d175ce9fd09434b, fe856be475f7cf5ffcde57341d175ce9fd09434bunaffected
LinuxLinux4.18, 0, 6.1.79, 6.6.18, 6.7.6, 6.8affected
Weakness

CWE details

No CWE listed

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