Security readout for executives and security teams
Plain-English summary
This flaw can make Cisco IOS XR routers running BGP with RPKI crash their BGP process. The business impact is routing instability or loss of availability, not data theft. Exploitation is constrained because the attacker needs to compromise or impersonate the RPKI validator path.
Executive priority
Treat this as a targeted availability risk for core routing infrastructure. It is not broadly exploitable from any internet host, but affected production routers using RPKI should be upgraded because a successful attack can destabilize BGP routing.
Technical view
Cisco IOS XR incorrectly handles a specific RPKI-to-Router Protocol packet header. A crafted RTR response from a compromised validator, or a man-in-the-middle impersonating it on an established RTR TCP connection, can crash BGP and cause repeated restarts. Cisco rates it CVSS 6.8, medium severity.
Likely exposure
Exposure is most likely on Cisco IOS XR deployments using the RPKI feature with affected releases listed in the source bundle, including 6.5.x, 6.6.x, 7.0.x, 7.1.x, and 7.2.x variants. Devices not using RPKI are not indicated as exposed by the provided sources.
Exploitation context
The provided sources do not report active exploitation, and the CVE is not marked KEV. Practical exploitation requires either a compromised RPKI validator server or successful impersonation of that validator over the established RTR TCP connection.
Researcher notes
The key conditions are RPKI enabled, affected IOS XR software, and attacker influence over the RTR validator response path. The source bundle names the bug class as CWE-617 and identifies availability impact only. No exploit code, public exploitation, or workaround is provided.
Mitigation direction
- Apply Cisco IOS XR software updates that address this vulnerability.
- Do not rely on a workaround; Cisco states none addresses this issue.
- Prioritize routers using RPKI for production BGP routing.
- Review RPKI validator integrity, access controls, and network path trust.
- Monitor BGP process restarts and routing instability during remediation.
Validation and detection
- Inventory Cisco IOS XR versions against the affected releases in the advisory.
- Confirm whether the RPKI feature is enabled on each IOS XR device.
- Verify the device is running a Cisco-fixed software release.
- Check logs and telemetry for BGP crashes or repeated restarts.
- Review configured RPKI validator endpoints and RTR session paths.
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-617: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-1440 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H2.24Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.8MediumVector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- cisco-sa-xrbgp-rpki-dos-gvmjqxbkCVE reference
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-xss-webui-gQLSFyPM</a></p><p>This advisory is part of the October 2021 release of the Cisco ASA, FTD, and FMC Security Advisory Bundled publication. For a complete list of the advisories and links to them, see <a href="https://sec.cloudapps.cisco.com/security/center/viewErp.x?alertId=ERP-74773">Cisco Event Response: October 2021 Cisco ASA, FMC, and FTD Software Security Advisory Bundled PublicationCVE reference
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-sdwan-sigverbypass-gPYXd6MkCVE reference
- https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-esa-sma-info-disclo-VOu2GHbZCVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Reachable Assertion
Reachable Assertion represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.