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CVE Record

CVE-2021-3998: A flaw was found in glibc.

A flaw was found in glibc. The realpath() function can mistakenly return an unexpected value, potentially leading to information leakage and disclosure of sensitive data.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

glibc is a core Linux runtime library. This flaw means software using realpath() could receive an unexpected result and leak sensitive information. Because glibc is broadly present across Linux systems, containers, and appliances, exposure can be widespread where affected versions are installed.

Executive priority

Prioritize remediation through normal high-severity Linux patch cycles, especially on internet-facing servers and shared container platforms. The main business risk is unintended disclosure of sensitive data from affected path-resolution behavior.

Technical view

CVE-2021-3998 is a CWE-125 information disclosure issue in glibc realpath(). The provided CVE data says glibc v2.33 and later are affected, with CVSS 3.1 score 7.5 and confidentiality impact rated high. Upstream Sourceware bug and commit references indicate the issue was addressed in glibc.

Likely exposure

Organizations using Linux distributions, containers, or appliances with glibc v2.33 or later may be exposed. Actual exposure depends on distribution backports, vendor package status, and whether applications call affected realpath() behavior.

Exploitation context

The supplied bundle does not show CISA KEV listing or cited evidence of active exploitation. Treat this as a high-impact confidentiality bug, but do not assume exploitation in the wild without vendor or threat-intelligence confirmation.

Researcher notes

Evidence is strongest for affected component, version range, CWE, and upstream fix references. The bundle does not provide exploit telemetry or detailed downstream fixed-version mapping, so validation should rely on distribution and appliance advisories.

Mitigation direction

  • Inventory systems, containers, and appliances using glibc v2.33 or later.
  • Apply vendor glibc security updates from the relevant Linux distribution or appliance vendor.
  • Check Red Hat, Debian, NetApp, and upstream glibc guidance for fixed package status.
  • Rebuild and redeploy container images that include affected glibc packages.

Validation and detection

  • Confirm installed glibc package versions against vendor security advisories.
  • Verify container base images have been rebuilt after glibc updates.
  • Review dependency and asset inventories for Linux appliances using vendor-supplied glibc.
  • Track exception records where vendor fixes are unavailable or pending.
Prepared
Confidence
medium
Sources
8

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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cwe · low confidence lookup

CWE-125: 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.

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cve · low confidence lookup

CVE-2021-3998 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.5 (3.1)
Known Exploited
No
Published

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

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.

1CVSS vectors
0Timeline events
0ADP providers
9Source links

CVSS vector scores

1 official score

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
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N3.93.6Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2021-3998Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

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

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/aglibcAffects glibc v2.33 and above.Listed
Weakness

CWE details

CWE-125

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

CWE-125 · source CWE mapping

Out-of-bounds Read

Out-of-bounds Read represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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