Threats / Cisco / CVE-2023-20109
CVE-2023-20109
· EUVD no mirror located
· GCVE no mirror located
Verified 2026-08-04
Cisco IOS and XE vulnerability
Cisco IOS and IOS XE contain an out-of-bounds write vulnerability in GET VPN that allows authenticated remote attackers with administrative control to execute code or crash devices.
Verdict
Today item — known-exploited.
An authenticated remote attacker with administrative privileges on a group member or key server can exploit an out-of-bounds write flaw to achieve remote code execution or denial of service on affected Cisco routing devices.
CISA KEV Yes · 2023-10-105EPSS 0.02344 (verify live)6CVSS 6.63CISA SSVC Exploitation: active · Automatable: no · Impact: total4
01
Is it exploitable?
— the evidence, ranked above the scoreReported exploitation
3 independent public reports of in-the-wild exploitation are cataloged.Distinct reporting sources (vendor, incident response, government); open them for the underlying claims.
Exploited in the wild
Listed in the CISA Known Exploited Vulnerabilities catalog (added 2023-10-10).
Probability (EPSS)
EPSS 0.02344 — modeled likelihood of exploitation activity.EPSS is a daily-changing model output — open the source for today's value.
Severity / affected
CVSS 6.6 (CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H) · Affected: Cisco, IOS and IOS XE. Confirm exact fixed builds in the vendor advisory.CVSS — CNA-assigned (CVE.org), version 3.1, set at disclosure.
Weakness (CWE)
Mapped to CWE-787 Out-of-bounds Write — weakness family: Memory safety.CWE — CNA-assigned (CVE.org); the weakness class drives how the flaw is exploited.
CISA SSVC (triage disposition)
Exploitation: active · Automatable: no · Technical Impact: totalCISA's own stakeholder-specific triage inputs, published in the CVE record (CISA Coordinator role). NOTE: this is CISA's three decision points; the final Act/Attend/Track decision also requires a Mission & Well-being input not published here, so no overall decision is asserted.
Currency of the record
CISA added this to its KEV catalog 13 days after the CVE record was published.KEV lag = CISA-KEV dateAdded − CVE.org datePublished; a floor on how long the known-exploited flaw sat in the public record before the federal catalog listed it. Severity/weakness here is CNA- or CISA-assigned (current at disclosure), independent of NVD's analysis backlog.
02
Who’s exploiting it?
— attribution turns risk into urgencyAttribution not established
No confirmed (advisory-backed) threat-actor attribution is established for this record. Absence of a named actor is not absence of compromise — see Coverage & confidence.
03
Why it matters
— the attack path, told twice: adversary, then board1
Front door — unauthenticated access narrative 1
Attacker
I gain administrative access to a GET VPN group member or key server through credential compromise or insider access.
Business
An insider or compromised administrator account provides the foothold needed to target core network infrastructure.
2
Keys to the kingdom — privilege/identity takeover narrative 2
Attacker
I craft a malicious packet that triggers an out-of-bounds write in the GET VPN processing logic on a remote device.
Business
The vulnerability allows direct code execution on critical routing devices that manage encrypted traffic flows.
3
Lateral reach — past segmentation narrative 3
Attacker
I execute arbitrary code with device privileges or force a crash to disrupt VPN operations.
Business
Compromise of VPN infrastructure can lead to data exfiltration, network segmentation bypass, or extended service outages.
04
What to do
— defensible action- Remediate per the vendor advisory — confirm the fixed build for your version and verify exposure.1
Say it to the boardA vulnerability with this evidence profile is a defensible budget line, not a backlog ticket — fund the change against the proof above.
05