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CVE Record

CVE-2026-44673: libyang: lyb_read_string() integer overflow → heap buffer overflow

libyang is a YANG data modeling language library. Prior to SO 5.2.15, lyb_read_string() in src/parser_lyb.c contains an integer overflow that results in a heap buffer overflow when parsing a maliciously crafted LYB binary blob. An attacker who can supply LYB data to any libyang consumer (NETCONF server, sysrepo, etc.) can trigger a crash or potential heap corruption. This vulnerability is fixed in SO 5.2.15.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A malicious LYB data file can crash software using vulnerable libyang versions and may corrupt memory. The main business risk is service disruption in network-management or YANG-processing systems that accept attacker-controlled LYB data. The supplied sources do not establish code execution.

Executive priority

Prioritize rapid remediation for exposed network-management infrastructure or critical services accepting untrusted LYB data. Handle internal systems through normal high-severity patching after confirming reachability. Escalate if crashes consistent with malicious LYB processing appear.

Technical view

Before SO 5.2.15, an integer overflow in lyb_read_string() within src/parser_lyb.c can cause a heap buffer overflow while parsing crafted LYB binary data. Affected consumers include libyang-dependent applications such as NETCONF servers and sysrepo when attacker-controlled LYB input reaches the parser.

Likely exposure

Exposure exists where libyang earlier than SO 5.2.15 is installed or bundled and a consumer processes untrusted LYB data. Internet-facing or otherwise remotely reachable consumers warrant particular attention. Presence of the library alone does not confirm an exploitable input path.

Exploitation context

The CVSS 3.1 score is 7.5, reflecting remotely reachable, low-complexity, unauthenticated denial-of-service potential. The bundle marks this CVE as absent from KEV and provides no cited evidence of active exploitation. Public exploit availability is not established.

Researcher notes

CWE-190 integer overflow precedes the heap overwrite. Available evidence supports reliable availability impact and possible heap corruption, but not confidentiality loss, integrity loss, or code execution. Analysis should focus on downstream reachability, bundled library versions, and whether application controls constrain LYB input size or origin.

Mitigation direction

  • Inventory libyang versions, including copies embedded in NETCONF, sysrepo, and other YANG-processing products.
  • Upgrade affected installations to SO 5.2.15 or a vendor-packaged release containing the fix.
  • Apply the applicable Red Hat erratum after confirming product and release scope.
  • Until updated, restrict untrusted LYB input and network access to exposed consumers where operationally feasible.
  • Monitor vendor guidance for downstream products that bundle libyang.

Validation and detection

  • Confirm runtime and packaged libyang versions are SO 5.2.15 or vendor-confirmed fixed builds.
  • Check manifests, container images, appliances, and software bills of materials for older bundled copies.
  • Identify services parsing LYB and determine whether untrusted or network-originated data can reach them.
  • Review crash telemetry for abnormal LYB-parsing failures; such findings alone do not prove exploitation.
  • Verify applicable vendor advisories and errata are installed across every supported environment.
Prepared
Confidence
high
Sources
4

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-190: Exact CWE lookup

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cve · low confidence lookup

CVE-2026-44673 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
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:N/I:N/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
2ADP providers
15Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: pocAutomatable: yesTechnical 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
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6GitHub_M
7.5CVSS 3.1HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H3.93.6redhat-SADP

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-44673Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

    Made public.

  3. CVE publishedCVE Program

    The CVE record was published.

  4. ADP timelineredhat-SADP

    Reported to Red Hat.

  5. CVE updatedCVE Program

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

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc
redhat-SADPlibyang: libyang: Denial of Service or arbitrary code execution via maliciously crafted LYB binary blob
other:Red Hat severity ratingcvssV3_1
  • 2026-05-14T21:01:08.333Z: Reported to Red Hat.
  • 2026-05-14T20:35:13.963Z: Made public.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
CESNETlibyang< SO 5.2.15Listed
Weakness

CWE details

CWE-190

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

CWE-190 · source CWE mapping

Integer Overflow or Wraparound

Integer Overflow or Wraparound represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.

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