Ios XrOperating system · Cisco
CVE-2025-20177
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedA vulnerability in the boot process of Cisco IOS XR Software could allow an authenticated, local attacker to bypass Cisco IOS XR image signature verification and load unverified software on an affected device. To exploit this vulnerability, the attacker must have root-system privileges on the affected device. This vulnerability is due to incomplete validation of files in the boot verification process. An attacker could exploit this vulnerability by manipulating the system configuration options to bypass some of the integrity checks that are performed during the boot process. A successful exploit could allow the attacker to control the boot configuration, which could enable them to bypass the requirement to run Cisco-signed images or alter the security properties of the running system. Note: Because exploitation of this vulnerability could result in the attacker bypassing Cisco image verification, Cisco has raised the Security Impact Rating (SIR) of this advisory from Medium to High.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceA vulnerability in Cisco IOS XR Software's boot process allows an authenticated attacker with root-system privileges to bypass image signature verification by manipulating system configuration options that control boot integrity checks. This enables loading unsigned software and altering the system's security properties.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Ios XrOperating system
< 7.11.21>= 24.2, < 24.2.2>= 24.3, < 24.3.2= 24.4CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- High
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Determine IOS XR versionExecute 'show version' or use 'admin show install active' to identify the installed IOS XR versionAffected if The installed version falls within < 7.11.21, >= 24.2 and < 24.2.2, >= 24.3 and < 24.3.2, or equals 24.4
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Verify root-system accessReview user accounts and privilege levels using 'show running-config' or 'show users' to identify accounts with root-system privilegesAffected if Accounts with root-system privileges exist and are accessible beyond the intended administrator group
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Inspect boot integrity configurationExamine boot-related configuration using 'show running-config' focusing on boot integrity, image verification, or secure boot settings such as 'boot integrity' or 'image verification' keywordsAffected if Boot integrity checks are disabled or set to allow unsigned images
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Check for unauthorized configuration changesCompare current configuration against known-good baselines using configuration management tools or 'show configuration commit list' to identify recent changes to boot-related settingsAffected if Recent configuration changes modified boot integrity or verification settings without documented approval
You are affected if your IOS XR version is within the affected ranges AND an attacker with root-system privileges could manipulate boot integrity configuration to bypass image signature verification.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped7.11.2124.2.224.3.2
Apply the Cisco-provided security update for IOS XR when available; restrict root-system access and monitor configuration changes for unauthorized modifications to boot-related settings.
For 7.x branch: 7.11.21 or later; For 24.2.x branch: 24.2.2 or later; For 24.3.x branch: 24.3.2 or later; For 24.4: version higher than 24.4 (e.g., 24.4.1)
- 1. Identify the current Cisco IOS XR version by running 'show version' in EXEC mode
- 2. Based on the current version, determine the appropriate upgrade path: for 7.x line upgrade to 7.11.21 or later, for 24.2.x upgrade to 24.2.2 or later, for 24.3.x upgrade to 24.3.2 or later, for 24.4 upgrade to version higher than 24.4
- 3. Download the appropriate fixed Cisco IOS XR software image from the Cisco Software Download Center (software.cisco.com)
- 4. Back up the current router configuration using 'admin backup' or 'copy running-config startup-config'
- 5. Verify the integrity of the downloaded image using Cisco's provided SHA256 checksum
- 6. Install the new IOS XR image following Cisco's standard upgrade procedures (typically using 'install add' and 'install activate' commands in admin mode)
- 7. After installation, verify the new version is running with 'show version'
- 8. Confirm the fix is applied by verifying that the boot integrity checks cannot be bypassed through configuration manipulation
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Ios Xr
Scoped from the published advisory
- Consultation4.0 h
- Implementation6.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,544.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2025-20177 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2025-20177 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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