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CVE Record

CVE-2026-45186: In libexpat before 2.8.1, the computational complexity of attribute name collision checks allows a denial o...

In libexpat before 2.8.1, the computational complexity of attribute name collision checks allows a denial of service via moderately sized crafted XML input.

HighCVSS 7.5Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

CVE-2026-45186 is a denial-of-service flaw in libexpat before 2.8.1. Crafted XML with attribute-name collisions can make parsing consume excessive CPU, potentially slowing or stopping services that accept XML from untrusted sources.

Executive priority

Prioritize remediation for internet-facing or partner-facing XML processing services. This is a high availability issue with easy remote triggering per CVSS, but current bundle evidence does not show active exploitation or confidentiality impact.

Technical view

The issue is classified as CWE-407: inefficient algorithmic complexity. Attribute name collision checks in libexpat before 2.8.1 can be driven into costly computation by moderately sized crafted XML input. CVSS 3.1 is 7.5, network-reachable, low complexity, no privileges, no user interaction, availability impact only.

Likely exposure

Exposure is most likely where applications, middleware, appliances, or OS packages use libexpat to parse attacker-supplied XML. The bundle names libexpat before 2.8.1 and includes Red Hat errata plus a Siemens advisory reference, indicating downstream vendor tracking.

Exploitation context

The source bundle does not state active exploitation, and KEV is false. The described attack is remote denial of service through crafted XML, not code execution or data theft. Evidence supports availability risk, but not weaponized exploitation in the wild.

Researcher notes

The CVE text centers on attribute-name collision complexity in libexpat before 2.8.1. The provided affected metadata is sparse and partly inconsistent with the description, so product scope should be confirmed through vendor advisories rather than inferred.

Mitigation direction

  • Upgrade libexpat to 2.8.1 or later where available.
  • Apply relevant vendor advisories for packaged or embedded libexpat.
  • Check Red Hat errata for affected supported platforms.
  • Review Siemens advisory if using Siemens products.
  • Limit or reject untrusted XML where upgrades are pending.
  • Monitor vendor guidance for product-specific fixes.

Validation and detection

  • Inventory direct and transitive libexpat usage.
  • Confirm deployed libexpat versions are 2.8.1 or later.
  • Identify services that parse externally supplied XML.
  • Check OS vendor security advisories against installed packages.
  • Review dependency scanners for CVE-2026-45186 findings.
  • Validate remediation in staging before production rollout.
Prepared
Confidence
medium
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-407: 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-2026-45186 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
4ADP providers
12Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical 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:H3.93.6redhat-SADP
2.9CVSS 3.1LowCVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L1.41.4mitre

Vulnerability scoring details

Base CVSS 3.1 score

7.5High
CVSS 3.1 vector shape for CVE-2026-45186Attack 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
CVECVE Program Container
redhat-SADPlibexpat: denial of service via crafted XML input
other:Red Hat severity ratingcvssV3_1
  • 2026-05-10T07:00:47.768Z: Reported to Red Hat.
  • 2026-05-10T06:36:16.927Z: Made public.
siemens-SADPADP container

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
libexpat projectlibexpat0unaffected
Weakness

CWE details

CWE-407

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