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CVE Record

CVE-2026-4878: Libcap: libcap: privilege escalation via toctou race condition in cap_set_file()

A flaw was found in libcap. A local unprivileged user can exploit a Time-of-check-to-time-of-use (TOCTOU) race condition in the `cap_set_file()` function. This allows an attacker with write access to a parent directory to redirect file capability updates to an attacker-controlled file. By doing so, capabilities can be injected into or stripped from unintended executables, leading to privilege escalation.

MediumCVSS 6.7Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This is a local privilege escalation flaw in libcap on listed Red Hat platforms. An attacker already on a system may misuse a race condition during file capability changes to alter the wrong executable’s privileges. It is not remotely exploitable from the network based on the provided data.

Executive priority

Treat as a scheduled but important patching item. It requires local access and a difficult race, reducing urgency versus remote flaws, but successful exploitation could compromise system integrity and confidentiality on high-value Linux hosts.

Technical view

CVE-2026-4878 is a CWE-367 TOCTOU race in libcap’s cap_set_file(). A low-privileged local user with write access to a parent directory may redirect capability updates to an attacker-controlled or unintended file, allowing capabilities to be injected or stripped and potentially escalating privileges.

Likely exposure

Exposure is likely on affected Red Hat Enterprise Linux 8, 9, and 10 systems and affected OpenShift Container Platform 4.13 through 4.17 RHCOS nodes that include the listed libcap or rhcos builds.

Exploitation context

The source data rates this CVSS 6.7 with local attack vector, high complexity, low privileges, and user interaction required. KEV is false, and the bundle provides no evidence of active exploitation or public weaponization.

Researcher notes

The key condition is attacker write access to a parent directory while cap_set_file() operates on a target path. The bundle does not provide proof-of-concept details, exploit telemetry, or non-Red Hat affected product confirmation.

Mitigation direction

  • Identify affected RHEL and OpenShift versions against the listed libcap and rhcos builds.
  • Apply the relevant Red Hat RHSA updates for each supported product stream.
  • Prioritize multi-user hosts, build systems, shared administration servers, and OpenShift worker nodes.
  • Review vendor guidance before using compensating controls not stated in the advisories.

Validation and detection

  • Confirm installed libcap or rhcos versions on affected Red Hat assets.
  • Map each asset to the matching Red Hat advisory and support stream.
  • Verify package or node updates completed successfully after maintenance.
  • Review local write permissions on directories involved in capability-management workflows.
Prepared
Confidence
high
Sources
12

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

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cwe · low confidence lookup

CWE-367: Exact CWE lookup

Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.

Open ATT&CK lookup
description · low confidence lookup

Privilege behavior lookup

The CVE wording references privilege impact, so privilege escalation and authorization behavior review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
description · low confidence lookup

Container behavior lookup

The affected technology mentions containers, so container-specific ATT&CK technique review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.

Open ATT&CK lookup
cve · low confidence lookup

CVE-2026-4878 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
Medium
CVSS
6.7 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/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
7Timeline events
3ADP providers
35Source links

SSVC decision data

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

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
6.7CVSS 3.1MediumCVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H0.85.9redhat
6.7CVSS 3.1MediumCVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:U/C:H/I:H/A:H0.85.9redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

6.7Medium
CVSS 3.1 vector shape for CVE-2026-4878Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:R/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. Source timelineredhat

    Reported to Red Hat.

  4. ADP timelineredhat-SADP

    Made public.

  5. Source timelineredhat

    Made public.

  6. CVE publishedCVE Program

    The CVE record was published.

  7. CVE updatedCVE Program

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

ADP provider summaries

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPlibcap: libcap: Privilege escalation via TOCTOU race condition in cap_set_file()
other:Red Hat severity ratingcvssV3_1
  • 2026-03-26T06:56:21.213Z: Reported to Red Hat.
  • 2026-04-06T00:00:00.000Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
Red HatRed Hat Enterprise Linux 10libcap, 0:2.69-7.el10_1.1affected
Red HatRed Hat Enterprise Linux 10libcap, 0:2.69-7.el10_2.1affected
Red HatRed Hat Enterprise Linux 10.0 Extended Update Supportlibcap, 0:2.69-7.el10_0.1affected
Red HatRed Hat Enterprise Linux 8libcap, 0:2.48-6.el8_10.1affected
Red HatRed Hat Enterprise Linux 8.6 Advanced Mission Critical Update Supportlibcap, 0:2.48-4.el8_6.1affected
Red HatRed Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-Onlibcap, 0:2.48-4.el8_6.1affected
Red HatRed Hat Enterprise Linux 8.8 Telecommunications Update Servicelibcap, 0:2.48-5.el8_8.1affected
Red HatRed Hat Enterprise Linux 8.8 Update Services for SAP Solutionslibcap, 0:2.48-5.el8_8.1affected
Red HatRed Hat Enterprise Linux 9libcap, 0:2.48-10.el9_7.1affected
Red HatRed Hat Enterprise Linux 9libcap, 0:2.48-10.el9_8.1affected
Red HatRed Hat Enterprise Linux 9libcap, 0:2.48-10.el9_7.1affected
Red HatRed Hat Enterprise Linux 9libcap, 0:2.48-10.el9_8.1affected
Red HatRed Hat Enterprise Linux 9.2 Update Services for SAP Solutionslibcap, 0:2.48-9.el9_2.1affected
Red HatRed Hat Enterprise Linux 9.4 Extended Update Supportlibcap, 0:2.48-9.el9_4.1affected
Red HatRed Hat Enterprise Linux 9.6 Extended Update Supportlibcap, 0:2.48-9.el9_6.1affected
Red HatRed Hat OpenShift Container Platform 4.13rhcos, 413.92.202606160406-0affected
Red HatRed Hat OpenShift Container Platform 4.14rhcos, 414.92.202606231112-0affected
Red HatRed Hat OpenShift Container Platform 4.15rhcos, 415.92.202606030318-0affected
Red HatRed Hat OpenShift Container Platform 4.16rhcos, 416.94.202606051757-0affected
Red HatRed Hat OpenShift Container Platform 4.17rhcos, 417.94.202606250942-0affected
Red HatRed Hat OpenShift Container Platform 4.18rhcos, 418.94.202606051320-0affected
Red HatRed Hat OpenShift Container Platform 4.19rhcos, 4.19.9.6.202606031700-0affected
Red HatCost Management 4costmanagement/costmanagement-metrics-rhel9-operator, 1780946239affected
Red HatRed Hat AI Inference Server 3.2rhaiis/model-opt-cuda-rhel9, 1780681984affected
Red HatRed Hat AI Inference Server 3.3rhaiis/model-opt-cuda-rhel9, 1782352950affected
Red HatRed Hat AI Inference Server 3.3rhaiis/vllm-spyre-rhel9, 1782352919affected
Red HatRed Hat AI Inference Server 3.3rhaiis/vllm-rocm-rhel9, 1782353093affected
Red HatRed Hat AI Inference Server 3.3rhaiis/vllm-cuda-rhel9, 1782352847affected
Red HatRed Hat Discovery 2discovery/discovery-server-rhel9, 1778101579affected
Red HatRed Hat Discovery 2discovery/discovery-ui-rhel9, 1778156756affected
Weakness

CWE details

CWE-367

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

CWE-367 · source CWE mapping

CWE mapping pending import

This CVE carries a CWE mapping that will resolve to a full Glexia CWE intelligence page after the official CWE import is complete.

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