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CVE Record

CVE-2023-6779: Glibc: off-by-one heap-based buffer overflow in __vsyslog_internal()

An off-by-one heap-based buffer overflow was found in the __vsyslog_internal function of the glibc library. This function is called by the syslog and vsyslog functions. This issue occurs when these functions are called with a message bigger than INT_MAX bytes, leading to an incorrect calculation of the buffer size to store the message, resulting in an application crash. This issue affects glibc 2.37 and newer.

HighCVSS 8.2Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

This is a glibc syslog flaw that can crash affected software when extremely large log messages are processed. Because glibc is a core Linux library, exposure depends on the operating system package and whether applications log attacker-controlled data. The supplied sources do not show confirmed active exploitation.

Executive priority

Treat as high priority for affected Linux fleets, especially externally exposed services and container images. The main business risk shown is service disruption, not data theft. Patch according to vendor guidance and close inventory gaps before assuming exposure is absent.

Technical view

CVE-2023-6779 is an off-by-one heap-based buffer overflow in glibc __vsyslog_internal(), reached through syslog and vsyslog. Sources describe incorrect buffer sizing for messages larger than INT_MAX bytes, causing application crashes. The bundle says glibc 2.37 and newer are affected, with Fedora affected and listed Red Hat Enterprise Linux releases unaffected.

Likely exposure

Highest concern is Linux systems using affected glibc packages where network-facing or untrusted-input services pass very large data into syslog-style logging. Red Hat’s listed RHEL packages are marked unaffected in the bundle; Fedora is marked affected.

Exploitation context

The CVSS vector rates this remotely reachable without privileges or user interaction, with high availability impact and low integrity impact. However, the evidence provided points mainly to denial-of-service via application crash. KEV is false, and no cited source in the bundle confirms active exploitation.

Researcher notes

The key uncertainty is practical reachability: affected glibc alone is insufficient without an application path that logs extremely large attacker-influenced messages. Do not generalize Red Hat’s unaffected status to other distributions. The supplied bundle does not establish public exploitation in the wild.

Mitigation direction

  • Inventory glibc versions and package status across Linux hosts and containers.
  • Apply vendor glibc updates where the vendor advisory marks the platform affected.
  • Prioritize internet-facing services that log attacker-controlled request or error data.
  • Check Fedora, Gentoo, NetApp, Siemens, and other vendor guidance for product-specific status.
  • For unaffected RHEL versions, retain evidence from Red Hat’s CVE page.

Validation and detection

  • Confirm installed glibc package versions against vendor advisories, not only upstream version numbers.
  • Check whether exposed applications call syslog or vsyslog with untrusted input paths.
  • Review crash telemetry for syslog-linked failures during oversized input handling.
  • Verify patched package installation through normal endpoint or container inventory.
  • Document exceptions where the vendor marks the product or package unaffected.
Prepared
Confidence
medium
Sources
10

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-122: Exact CWE lookup

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cve · low confidence lookup

CVE-2023-6779 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
8.2 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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.

1CVSS vectors
5Timeline events
3ADP providers
10Source links

SSVC decision data

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

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
8.2CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H3.94.2redhat

Vulnerability scoring details

Base CVSS 3.1 score

8.2High
CVSS 3.1 vector shape for CVE-2023-6779Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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. Source timelineredhat

    Reported to Red Hat.

  2. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  3. Source timelineredhat

    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

CVECVE Program Container
CISA-ADPCISA ADP Vulnrichment
other:ssvc
siemens-SADPADP container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
n/aglibc2.39Listed
Red HatRed Hat Enterprise Linux 6compat-glibcunaffected
Red HatRed Hat Enterprise Linux 6glibcunaffected
Red HatRed Hat Enterprise Linux 7compat-glibcunaffected
Red HatRed Hat Enterprise Linux 7glibcunaffected
Red HatRed Hat Enterprise Linux 8glibcunaffected
Red HatRed Hat Enterprise Linux 9glibcunaffected
FedoraFedoraglibcaffected
Weakness

CWE details

CWE-122

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

CWE-122 · source CWE mapping

Heap-based Buffer Overflow

Heap-based Buffer Overflow represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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