Retrospective for 2026-08-25, compiled on 27 October 2026. The date identifies the day being analysed; source publication and revision dates are recorded below.
What this advisory changes in your environment
The starting point is CERTFR-2026-AVI-1077, published on 2026-08-25. Its scope includes IOS XE Software. Reported consequences are impact requiring vendor clarification, security control bypass. These statements apply to the advisory’s scope; they do not assign every consequence to every product or CVE.
This case focuses on IOS XE Software. Locate that edition in live installations, deployment images and actual dependencies, rather than treating every product from Cisco as equivalent.
Products and versions to examine
- Reference
- CERTFR-2026-AVI-1077
- Source first published
- 2026-08-25
- Latest source revision available for this day
- 2026-08-25
- Named components
- IOS XE Software
- CVE identifiers
- CVE-2026-20270, CVE-2026-20267, CVE-2026-20271, CVE-2026-20269, CVE-2026-20273, CVE-2026-20272, CVE-2026-20268
| Component | Published condition |
|---|---|
| IOS XE Software | 26.1.x : < 26.1.2 |
| IOS XE Software | 17.12.x : < 17.12.8 |
| IOS XE Software | 17.9.x : < 17.9.10 |
| IOS XE Software | 17.15.x : < 17.15.6 |
For IOS XE Software, the published condition is “26.1.x : < 26.1.2”. Compare the version actually loaded with that condition within its own release branch. A fix installed on another edition of IOS XE Software does not close this case.
Mechanism and prerequisites
A security bypass challenges a trust boundary. Verify server-side authorisation decisions and alternative paths; hiding an interface is not an access restriction.
For CERTFR-2026-AVI-1077, the retained documents do not provide a suitably dated primary CVE record to establish this case’s prerequisites. Required authentication, user interaction and active exploitation therefore remain unestablished here; they are not inferred from IOS XE Software or the risk category alone.
Choose the appropriate intervention
- Locate IOS XE Software instances, running releases and service owners. Record condition 26.1.x : < 26.1.2 in the ticket alongside reference CERTFR-2026-AVI-1077.
- Compare the installed branch with the vendor’s IOS XE Software release notes. Prepare the package for that branch and a dependent-service test, retaining the pre-change state.
- After changing IOS XE Software, capture the loaded version again and verify the workflow below. Any exception needs an owner, an exposure-reduction measure and an expiry date.
Verify the fix in a real workflow
Validation scenario to adapt for IOS XE Software: On a test device using IOS XE Software, record the system version and patch level after restart. Check managed applications, corporate network access and account recovery; distinguish application updates from operating-system updates. This is a proposed defensive check, not a claim that testing was performed against third-party systems.
Limit of case CERTFR-2026-AVI-1077: this analysis replaces neither vendor prerequisites nor investigation of your logs. Only documented versions are reproduced; no attack date or victim is invented.
Questions specific to this case
Which condition should be checked for IOS XE Software?
Advisory CERTFR-2026-AVI-1077 states: IOS XE Software — 26.1.x : < 26.1.2. Check the edition and running release; do not extend the published boundary to branches absent from the advisory.
What is still needed to assess IOS XE Software exposure?
For IOS XE Software, establish the running version, the path to the component and process permissions. The sources retained for CERTFR-2026-AVI-1077 do not establish every prerequisite or active exploitation.
Sources and related reading
Practical guide : Deploy phishing-resistant authentication with safe recovery
Explore the decision addressed in this case
Complete source advisory inventory
The article table may be an extract. These lists contain every affected-system entry and CVE in the specified advisory revision. They are not an inventory of your assets and do not map every CVE to every product.
Official source · CERTFR-2026-AVI-1077
Advisory revision : · Checked on :
Affected systems · 5
Original French wording is retained to avoid ambiguous translations of version conditions.
- IOS XE Software versions 17.18 antérieures à 17.18.4 ou 17.18.4a
- IOS XE Software versions 26.1.x antérieures à 26.1.2
- IOS XE Software versions 17.12.x antérieures à 17.12.8
- IOS XE Software versions 17.9.x antérieures à 17.9.10
- IOS XE Software versions 17.15.x antérieures à 17.15.6