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CVE Record

CVE-2026-20027: Cisco Snort DCERPC Stub Data Out of Bounds Read

Multiple Cisco products are affected by a vulnerability in the processing of DCE/RPC requests that could allow an unauthenticated, remote attacker to cause the Snort 3 Detection Engine to leak sensitive information or to restart, resulting in an interruption of packet inspection. This vulnerability is due to an error in buffer handling logic when processing DCE/RPC requests, which can result in a buffer out-of-bounds read. An attacker could exploit this vulnerability by sending a large number of DCE/RPC requests through an established connection that is inspected by Snort 3. A successful exploit could allow the attacker to obtain sensitive information in the Snort 3 data stream.

MediumCVSS 5.3Not KEV-listedUpdated
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Glexia's TakeAutomated analysismoderate

Security readout for executives and security teams

Plain-English summary

This vulnerability affects Cisco products using the Snort 3 detection engine. A remote unauthenticated attacker could cause Snort to expose sensitive data from inspected traffic or restart, temporarily interrupting packet inspection. Business urgency is moderate: impact is limited, but affected firewalls or IPS engines sit in sensitive network paths.

Executive priority

Treat as a scheduled but important security maintenance item. Prioritize firewalls and IPS deployments in sensitive network paths because packet inspection reliability and data confidentiality are involved. Escalate if Cisco guidance identifies your exact versions as affected and no compensating controls exist.

Technical view

CVE-2026-20027 is an out-of-bounds read in Snort 3 DCE/RPC request processing, caused by buffer handling logic. Exploitation requires DCE/RPC requests over an established connection inspected by Snort 3. Cisco lists affected Secure Firewall Threat Defense and UTD SNORT IPS Engine Software versions. CVSS is 5.3, with low confidentiality impact and no integrity or availability score impact.

Likely exposure

Exposure is most likely where affected Cisco FTD or UTD SNORT IPS Engine versions inspect DCE/RPC traffic. Internet exposure depends on traffic paths and inspection policy, not just device management access. Organizations with broad east-west inspection or Windows/RPC-heavy environments should validate quickly.

Exploitation context

The sources do not indicate active exploitation, and CISA KEV status is false in the provided data. The attack is remote and unauthenticated but depends on traffic being inspected by Snort 3 over an established connection. Successful exploitation may leak sensitive data in the Snort data stream or restart inspection.

Researcher notes

Public details identify the bug class and trigger area but do not provide proof-of-concept details in the source bundle. Avoid assuming exploit availability. Focus research on affected-version confirmation, inspection-path exposure, and Cisco advisory updates for fixed release mapping or operational mitigations.

Mitigation direction

  • Review Cisco advisory cisco-sa-snort3-dcerpc-vulns-J9HNF4tH for fixed releases and official workarounds.
  • Upgrade affected Cisco FTD and UTD SNORT IPS Engine deployments per Cisco guidance.
  • Prioritize devices inspecting DCE/RPC traffic across sensitive or high-volume network segments.
  • Monitor for Snort 3 restarts and unexpected packet inspection interruptions.

Validation and detection

  • Inventory Cisco FTD and UTD SNORT IPS Engine versions against Cisco’s affected version lists.
  • Confirm whether Snort 3 inspection is enabled on relevant traffic paths.
  • Identify policies or zones where DCE/RPC traffic is inspected.
  • Review operational logs for Snort restarts or unusual DCE/RPC inspection activity.
Prepared
Confidence
medium
Sources
3

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 · medium confidence lookup

CWE-200: Information exposure and cloud metadata lookup

Information exposure and SSRF weaknesses can make discovery, cloud metadata, and credential material review relevant. 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-2026-20027 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
Medium
CVSS
5.3 (3.1)
Known Exploited
No
Published

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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
2Source 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
5.3CVSS 3.1MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N3.91.4Primary CVE score

Vulnerability scoring details

Base CVSS 3.1 score

5.3Medium
CVSS 3.1 vector shape for CVE-2026-20027Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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
CiscoCisco Secure Firewall Threat Defense (FTD) Software7.0.0, 7.0.0.1, 7.0.1, 7.1.0, 7.0.1.1, 7.1.0.1, 7.0.2, 7.2.0, 7.0.2.1, 7.0.3, 7.1.0.2, 7.2.0.1, 7.0.4, 7.2.1, 7.0.5, 7.3.0, 7.2.2, 7.2.3, 7.3.1, 7.1.0.3, 7.2.4, 7.0.6, 7.2.5, 7.2.4.1, 7.3.1.1, 7.4.0, 7.0.6.1, 7.2.5.1, 7.4.1, 7.2.6, 7.0.6.2, 7.4.1.1, 7.2.7, 7.2.5.2, 7.3.1.2, 7.2.8, 7.6.0, 7.4.2, 7.2.8.1, 7.0.6.3, 7.4.2.1, 7.2.9, 7.0.7, 7.7.0, 7.4.2.2, 7.2.10, 7.6.1, 7.4.2.3, 7.0.8, 7.6.2, 7.7.10, 7.0.8.1, 7.6.2.1, 7.7.10.1, 7.4.2.4, 7.2.10.2, 7.4.3unknown
CiscoCisco UTD SNORT IPS Engine Software3.17.1S, 16.12.3, Fuji-16.9.5, 16.12.4, 17.3.1a, 16.6.6, 16.12.2, Fuji-16.9.6, 3.17.0S, Fuji-16.9.3, Denali-16.3.7, Fuji-16.9.2, Fuji-16.9.4, Everest-16.6.4, Everest-16.6.3, 16.6.5, Denali-16.3.5, 17.2.1r, 17.1.1, Everest-16.6.2, 16.6.7a, Denali-16.3.4, 16.6.1, Denali-16.3.9, Denali-16.3.3, 16.12.1a, 17.3.2, 17.4.1a, 16.12.5, 17.5.1, Fuji-16.9.7, 16.6.9, 17.3.3, 17.5.1a, 17.3.4, 17.3.4a, 17.4.2, 17.4.1b, 17.6.1a, 16.6.10, 17.7.1a, 16.12.6, Fuji-16.9.8, 17.6.2, 17.8.1a, 16.12.7, 17.3.5, 17.6.3, 17.6.3a, 17.7.2, 17.9.1a, 17.6.4, 17.10.1a, 17.3.6, 16.12.8, 17.3.7, 17.9.2a, 17.6.5, 17.11.1a, 17.9.3a, 17.12.1a, 17.9.4, 17.6.6, 17.3.8, 17.3.8a, 17.6.6a, 17.9.4a, 17.12.2, 17.13.1a, 17.9.5a, 17.12.3, 17.6.7, 17.14.1a, 17.12.4, 17.12.3a, 17.15.1a, 17.6.8, 17.9.6, 17.6.8a, 17.16.1a, 17.9.5e, 17.12.4a, 17.15.2c, 17.9.5f, 17.12.4b, 17.15.2a, 17.12.5, 17.17.1, 17.12.5a, 17.9.7a, 17.15.3a, 17.15.3, 17.12.5b, 17.12.5c, 17.15.4, 17.9.7b, 17.18.1, 17.18.1a, 17.12.6, 17.9.8, 17.15.4c, 17.12.5d, 17.18.2unknown
Weakness

CWE details

CWE-200

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