CVE-2023-20135

HIGH
7
CVSS Score
Published: September 13, 2023 at 04:38 PM UTC
Updated: June 17, 2026 at 05:29 AM UTC
1 product affected across 1 vendorIOS Xr

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Severity
HIGH7
Exploit prediction
EPSS 0.1%
SSVC
No known exploit

Description

A vulnerability in Cisco IOS XR Software image verification checks could allow an authenticated, local attacker to execute arbitrary code on the underlying operating system. This vulnerability is due to a time-of-check, time-of-use (TOCTOU) race condition when an install query regarding an ISO image is performed during an install operation that uses an ISO image. An attacker could exploit this vulnerability by modifying an ISO image and then carrying out install requests in parallel. A successful exploit could allow the attacker to execute arbitrary code on an affected device.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

7.5.2 ≤ v < 7.67.7 ≤ v < 7.10.17.5.27.5.37.5.47.7.17.7.27.7.217.8.17.8.27.9.17.9.2
Affected range stops below 7.10.1, so it looks safe — our inference, not a vendor statement
Affected range stops below 7.6, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

Attack Vector
LOCAL
Complexity
HIGH
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-347CWE-367

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