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PatchSiren cyber security CVE debrief

CVE-2017-3803 Cisco CVE debrief

CVE-2017-3803 is a Cisco IOS Software issue affecting Cisco 2960X and 3750X switches. According to the NVD record and Cisco advisory references, an unauthenticated adjacent attacker could trigger a memory leak in the software forwarding queue that may eventually cause a partial denial of service condition. The published CVSS v3.0 vector reflects adjacent attack conditions and availability impact only.

Vendor
Cisco
Product
Unknown
CVSS
MEDIUM 4.7
CISA KEV
Not listed in stored evidence
Original CVE published
2017-01-26
Original CVE updated
2026-05-13
Advisory published
2017-01-26
Advisory updated
2026-05-13

Who should care

Network and infrastructure teams running Cisco IOS on affected 2960X or 3750X switches, especially in environments where untrusted devices can share the same Layer 2 segment.

Technical summary

The vulnerability is described as a memory leak in the IOS software forwarding queue. NVD classifies the weakness as CWE-772 (Missing Release of Resource after Effective Lifetime). The supplied record lists affected releases 15.2(2)E3 and 15.2(4)E1, with fixed releases including 15.2(2)E6, 15.2(4)E3, 15.2(5)E1, 15.2(5.3.28i)E1, 15.2(6.0.49i)E, and 3.9(1)E. The CVSS vector is CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:L.

Defensive priority

Medium. The issue is unauthenticated and can be triggered by an adjacent attacker, but the impact is limited to availability and described as partial DoS rather than full device compromise.

Recommended defensive actions

  • Inventory Cisco 2960X and 3750X switches and confirm the running IOS release.
  • Upgrade any affected devices to a fixed release listed in the supplied record.
  • Prioritize remediation on switches exposed to untrusted adjacent networks or shared Layer 2 segments.
  • Monitor for abnormal resource growth or instability on affected switches until patched.
  • Review Cisco's advisory and vendor guidance before scheduling maintenance windows.

Evidence notes

This debrief is based on the supplied NVD record for CVE-2017-3803 and the Cisco advisory references embedded in that record. The key facts used are: unauthenticated adjacent attack conditions, memory leak in the software forwarding queue, partial DoS impact, affected and fixed releases, and the NVD-assigned CWE-772 classification. No advisory body text was supplied, so mitigation details are limited to version-based upgrading and the referenced vendor documentation.

Sources and references

Verified primary and authoritative sources

  • CVE-2017-3803 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2017-3803

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2017-3803 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2017-3803

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.