Service interruption and data modification via predictable values
Published Sep 2, 2026 · Updated Sep 2, 2026
Protection mechanism failure in Cisco IOS XR Software allows remote attackers to alter data and interrupt service via predictable values. Cisco has not disclosed which functional area generates insufficiently random values or how those values defeat its protection mechanism. Network access without authentication or user interaction is sufficient, and every release is affected regardless of device configuration.
Summary
What happened
Protection mechanism failure in Cisco IOS XR Software allows remote attackers to alter data and interrupt service via predictable values. Cisco has not disclosed which functional area generates insufficiently random values or how those values defeat its protection mechanism. Network access without authentication or user interaction is sufficient, and every release is affected regardless of device configuration.
The record
- CVE
- CVE-2026-20277
- Published
- Sep 2, 2026
- Updated
- Sep 2, 2026
- Vendor
- ClamAV
- Product
- Cisco IOS XR Software
- Classifications
- CWE-693
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 2, 2026CVE publishedPublication date reported by the CVE source.
- Sep 2, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
Compare your product and version with the public record. A matching version still requires validation against your environment.
Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=24.1.1
- Affected versionversion=24.1.2
- Affected versionversion=24.2.1
- Affected versionversion=24.2.11
- Affected versionversion=24.2.2
- Affected versionversion=24.2.20
- Affected versionversion=24.2.21
- Affected versionversion=24.3.1
- Affected versionversion=24.3.2
- Affected versionversion=24.3.20
- Affected versionversion=24.3.30
- Affected versionversion=24.4.1
- Affected versionversion=24.4.10
- Affected versionversion=24.4.15
- Affected versionversion=24.4.2
- Affected versionversion=24.4.30
- Affected versionversion=25.1.1
- Affected versionversion=25.1.2
- Affected versionversion=25.1.30
- Affected versionversion=25.2.1
- Affected versionversion=25.2.15
- Affected versionversion=25.2.2
- Affected versionversion=25.2.30
- Affected versionversion=25.3.1
- Affected versionversion=25.3.15
- Affected versionversion=25.4.1
- Affected versionversion=25.4.2
- Affected versionversion=25.4.201
- Affected versionversion=25.4.30
- Affected versionversion=26.1.1
- Affected versionversion=26.1.2
- Affected versionversion=26.2.1
- Affected versionversion=26.2.100
- Affected versionversion=26.2.101
- Affected versionversion=6.5.25
- Affected versionversion=6.5.26
- Affected versionversion=6.5.28
- Affected versionversion=6.5.29
- Affected versionversion=6.5.31
- Affected versionversion=6.5.32
- Affected versionversion=6.5.33
- Affected versionversion=6.5.35
- Affected versionversion=6.5.351
- Affected versionversion=6.5.352
- Affected versionversion=6.5.353
- Affected versionversion=6.5.90
- Affected versionversion=6.7.1
- Affected versionversion=6.7.2
- Affected versionversion=6.7.3
- Affected versionversion=6.7.35
- Affected versionversion=6.7.4
- Affected versionversion=6.8.1
- Affected versionversion=6.8.2
- Affected versionversion=6.9.1
- Affected versionversion=6.9.2
- Affected versionversion=7.0.0
- Affected versionversion=7.0.1
- Affected versionversion=7.0.11
- Affected versionversion=7.0.12
- Affected versionversion=7.0.14
- Affected versionversion=7.0.2
- Affected versionversion=7.0.90
- Affected versionversion=7.10.1
- Affected versionversion=7.10.2
- Affected versionversion=7.1.1
- Affected versionversion=7.11.1
- Affected versionversion=7.11.2
- Affected versionversion=7.11.21
- Affected versionversion=7.1.15
- Affected versionversion=7.1.2
- Affected versionversion=7.1.25
- Affected versionversion=7.1.3
- Affected versionversion=7.2.0
- Affected versionversion=7.2.1
- Affected versionversion=7.2.12
- Affected versionversion=7.2.2
- Affected versionversion=7.3.1
- Affected versionversion=7.3.15
- Affected versionversion=7.3.16
- Affected versionversion=7.3.2
- Affected versionversion=7.3.27
- Affected versionversion=7.3.3
- Affected versionversion=7.3.4
- Affected versionversion=7.3.5
- Affected versionversion=7.3.6
- Affected versionversion=7.4.1
- Affected versionversion=7.4.15
- Affected versionversion=7.4.16
- Affected versionversion=7.4.2
- Affected versionversion=7.5.1
- Affected versionversion=7.5.12
- Affected versionversion=7.5.2
- Affected versionversion=7.5.3
- Affected versionversion=7.5.4
- Affected versionversion=7.5.5
- Affected versionversion=7.5.52
- Affected versionversion=7.6.1
- Affected versionversion=7.6.15
- Affected versionversion=7.6.2
- Affected versionversion=7.6.3
- Affected versionversion=7.7.1
- Affected versionversion=7.7.2
- Affected versionversion=7.7.21
- Affected versionversion=7.8.1
- Affected versionversion=7.8.12
- Affected versionversion=7.8.2
- Affected versionversion=7.8.22
- Affected versionversion=7.8.23
- Affected versionversion=7.9.1
- Affected versionversion=7.9.2
- Affected versionversion=7.9.21
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
No public exploit references are available in this record.
Labels summarize the accepted research assessment. They do not indicate a test against your environment.
Technologies
Your stack
See the directory against your own environment.
Your stack
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