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CVE-2026-109399

SWUpdate through 2026.05.1 CMS Signature Verification Bypass via Embedded Intermediates

CVSS score

9.2

EPSS probability

—

Risk score

0.9

Published

19 h ago

Official patch verified

Etkilenen ürün ve sürüm için yayımlanan güvenlik güncellemesini uygulayın.

Impact on My Inventory

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Vulnerability description

CVE AI research

The stored explanation is shown at once; refreshing evaluates the sources again.

DayBreach AI Explanation

Verified against sources

SWUpdate CVE-2026-109399 CMS Signature Verification Bypass Vulnerability

Sources read

2

Source agreement

0/2

Evidence confidence

%39

Short explanation

SWUpdate through version 2026.05.1 contains an improper certificate validation vulnerability by trusting untrusted X.509 certificates embedded in CMS SignedData for chain building. This vulnerability allows attackers to install malicious updates.

Why does it matter?

Attackers holding a signing key from a sibling intermediate under the same root can embed that intermediate in the signature to install malicious updates, posing critical confidentiality, integrity, and availability risks.

What should be done?

  • Follow vendor advisories to apply fixes
  • Review the provided patch references
Note on uncertainty

3 alanda kaynak uyuşmazlığı var. DayBreach bu değerleri saklamadı; kaynak karşılaştırması aşağıda gösteriliyor.

Chain of evidence and sources3 verified claims

SWUpdate 2026.05.1 ve önceki sürümleri, crypto/swupdate_cms_verify_openssl.c dosyasında uygunsuz sertifika doğrulaması içermektedir.

Aynı root altındaki bir kardeş ara sertifikanın imzalama anahtarına sahip saldırganlar, imzaya ara sertifikayı gömerek kötü amaçlı güncellemeler yükleyebilir.

Kaynaklar arasında CVSS taban puanı konusunda çelişki bulunmakta olup, değerler 9.2 ve 8.1 olarak bildirilmektedir.

Show the technical text from the sources

SWUpdate through 2026.05.1 contains an improper certificate validation vulnerability in crypto/swupdate_cms_verify_openssl.c that trusts untrusted X.509 certificates embedded in CMS SignedData for chain building. Attackers holding a signing key from a sibling intermediate under the same root can embed that intermediate in the signature to install malicious updates.

CVSS vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CWE: CWE-295

Explanation produced with the local gemini-flash-lite-latest model. Numerical metrics and the KEV, patch and exploit statuses are not determined by AI.

IMPACT: Affected Products and Software

Affected Products

The following products are affected by CVE-2026-109399 vulnerability. Where our threat engine knows the exact affected versions, they are listed below.

IDVENDORPRODUCTACTION
1sbabicswupdate View
Total affected vendors: 1|Products: 1

RED HAT CSAF/VEX: Product Impact Check

Red Hat has not yet published a CSAF/VEX impact record for this CVE. This does not mean “not affected”.

SCORING: CVSS from Multiple Sources

CVSS Scores

The Common Vulnerability Scoring System is a standardised framework for assessing the severity of vulnerabilities in software and systems. We collect and display CVSS scores from several sources for each CVE.

SCOREVERSIONSEVERITYVECTORSOURCE
9.2CVSS V40CRITICALCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:XNVD
9.2CVSS V4_0CRITICALCVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:NCVE CNA
8.1CVSS V31HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:HNVD
8.1CVSS V3_1HIGHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:HCVE CNA

Patch and Remediation Guide

Solution & Remediation Advisory

Patch verified

2 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

cvelist

CNA çözüm referansı

Open source
reference

Yama veya çözüm referansı

Open source
Confirm the affected product and version against the source evidence above.
Restrict access to internet-facing services and apply network segmentation.
Apply the official update named in the evidence only to the matching product and version.
Monitor server logs and network endpoints for signs of anomalous execution.

Public exploit and active exploitation status

Verified exploit intelligence

No verified public PoC, exploit repository or Metasploit module has been found for this CVE yet.

Weakness Classification and Attack Patterns (CWE & CAPEC)

CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorises the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-109399 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-109399 weaknesses.

Attack Vector and Accessibility

ExposureAğ üzerinden
PermissionsGerekmiyor
UserGerekmiyor

Official Sources and Advisories

CVSS Vector Radar Chart

9.2 / 10
Attack VectorNetworkComplexityHighPrivilegesNoneUser Interact.NoneConfidentialityHighIntegrityNoneAvailabilityHigh

Vulnerability Scoring Details

CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
Attack VectorNetwork
Attack ComplexityHigh
Privileges RequiredNone required
User InteractionNone required
Confidentiality (Gizlilik)High
Integrity (Bütünlük)None
Availability (Erişilebilirlik)High

Yama doğrulandı

2 doğrulanmış yama veya düzeltilmiş sürüm kanıtı bulundu.

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Weakness Type (CWE & CAPEC)

Get this vulnerability through the API

Affected products, version ranges, exploitation status and patch information in a single request, with a free key.

curl -H "x-api-key: $DAYBREACH_API_KEY" \
  "https://api.enginteksut.com.tr/api/v1/intel/cves/CVE-2026-109399"