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CVE Record

CVE-2026-43178: procfs: fix possible double mmput() in do_procmap_query()

In the Linux kernel, the following vulnerability has been resolved: procfs: fix possible double mmput() in do_procmap_query() When user provides incorrectly sized buffer for build ID for PROCMAP_QUERY we return with -ENAMETOOLONG error. After recent changes this condition happens later, after we unlocked mmap_lock/per-VMA lock and did mmput(), so original goto out is now wrong and will double-mmput() mm_struct. Fix by jumping further to clean up only vm_file and name_buf.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A local Linux user may trigger faulty kernel memory-management cleanup by supplying an incorrectly sized procfs process-map query buffer. The kernel can release a process memory descriptor twice, potentially compromising confidentiality, integrity, or availability. Network access alone is insufficient; an attacker needs local, low-privileged access.

Executive priority

Treat as a high-priority local privilege-boundary risk, especially on shared or externally accessible compute. It is less urgent than remotely exploitable kernel flaws on systems without untrusted local execution. Patch through supported distribution channels after confirming applicability; no active exploitation is established in the supplied evidence.

Technical view

In do_procmap_query(), an undersized build-ID buffer causes -ENAMETOOLONG after mmap or per-VMA locking is released and mmput() has run. The former error path performs another mmput() on the same mm_struct. The correction redirects cleanup to release only vm_file and name_buf.

Likely exposure

Exposure is concentrated on systems allowing untrusted or compromised local users to reach the affected procfs interface. The bundle marks Linux versions 6.19, 6.12.75, 6.18.16, 6.19.6, and 7.0 as affected, but its version presentation is ambiguous. Confirm distribution backports and running kernel builds with vendor guidance.

Exploitation context

The CVSS 3.1 score is 7.8 with local access, low complexity, low privileges, and no user interaction. The source bundle provides no evidence of public exploitation or inclusion in CISA's Known Exploited Vulnerabilities catalog. Practical exploitability and demonstrated impact are not established by the supplied evidence.

Researcher notes

The trigger is an incorrectly sized build-ID buffer in PROCMAP_QUERY, producing -ENAMETOOLONG after the first mmput(). Analysis should focus on exact introduction and stable-backport boundaries, which are not clearly represented in the bundle's affected-version list. The cited kernel commits are the authoritative correction references; no proof-of-concept or observed exploitation is supplied.

Mitigation direction

  • Apply a vendor-supported kernel update containing the cited procfs correction.
  • Reboot into the updated kernel and confirm the running version.
  • Check distribution advisories for backport status and affected build mappings.
  • Prioritize multi-user, shared-hosting, and other systems permitting untrusted local execution.

Validation and detection

  • Inventory running Linux kernel versions across affected systems.
  • Compare exact distribution builds against vendor advisories and backport records.
  • Confirm the installed kernel contains the applicable cited stable commit.
  • Verify systems booted the remediated kernel after updating.
  • Review local-access exposure while remediation remains pending.
Prepared
Confidence
medium
Sources
9

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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cwe · low confidence lookup

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CVE-2026-43178 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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
5Timeline events
1ADP providers
8Source links

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
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux
7CVSS 3.1HighCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H15.9redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2026-43178Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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. ADP timelineredhat-SADP

    Reported to Red Hat.

  3. ADP timelineredhat-SADP

    Made public.

  4. CVE publishedCVE Program

    The CVE record was published.

  5. CVE updatedCVE Program

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

ADP provider summaries

redhat-SADPkernel: procfs: fix possible double mmput() in do_procmap_query()
other:Red Hat severity ratingcvssV3_1
  • 2026-05-06T00:00:00.000Z: Reported to Red Hat.
  • 2026-05-06T00:00:00.000Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxb9b97e6aeb534315f9646b2090d1a5024c6a4e82, cbc03ce3e6ce7e21214c3f02218213574c1a2d08, b5cbacd7f86f4f62b8813688c8e73be94e8e1951, b5cbacd7f86f4f62b8813688c8e73be94e8e1951, 6.12.70, 6.18.10unaffected
LinuxLinux6.19, 0, 6.12.75, 6.18.16, 6.19.6, 7.0affected
Weakness

CWE details

CWE-1341

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CWE-1341 · source CWE mapping

Multiple Releases of Same Resource or Handle

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