Security readout for executives and security teams
Plain-English summary
This issue concerns trust between network routing peers. BIRD through 2.0.7 lacked password authentication for BGP peers, so some deployments using BIRD could be exposed to route redirection, denial of service, or information disclosure if an attacker can reach and influence BGP peering.
Executive priority
Treat this as a targeted infrastructure exposure issue, not a broad internet emergency. Prioritize review where BIRD controls production routing, Kubernetes networking, or sensitive traffic paths. Business impact could be outage or traffic exposure if routing trust is abused.
Technical view
CVE-2021-26928 is a CWE-306 authentication weakness in BIRD through 2.0.7: no functionality for password authentication of BGP peers. The CVSS vector is AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:H. Products embedding BIRD, including some Tigera configurations per the CVE note, may be affected, but the affected-product data is incomplete.
Likely exposure
Exposure is most likely in infrastructure using BIRD through 2.0.7 for BGP, or vendor products that embed BIRD. The source bundle does not identify precise products, versions, or configurations beyond that scope.
Exploitation context
The source bundle does not show active exploitation, and KEV is false. The plausible impact described is route redirection leading to denial of service or information disclosure, with high attack complexity and low privileges in the CVSS vector.
Researcher notes
The CVE record includes a disputed responsibility note involving Tigera and a CyberArk Kubernetes networking research reference. Do not assume all Tigera deployments are affected. Confirm actual BIRD use, version, BGP exposure, and vendor-specific guidance before assigning remediation ownership.
Mitigation direction
- Inventory BIRD deployments and products that bundle BIRD for BGP routing.
- Check vendor guidance for supported upgrades, configuration changes, or compensating controls.
- Restrict BGP peering access to explicitly trusted networks and peers.
- Review route filtering and monitoring controls around BGP-learned routes.
- Prioritize environments where BGP affects production Kubernetes or service routing.
Validation and detection
- Confirm deployed BIRD versions and whether any are through 2.0.7.
- Identify vendor products that embed or manage BIRD in your environment.
- Review BGP peer configurations for unauthenticated or broadly reachable peering.
- Verify only expected peers can establish BGP sessions.
- Review routing changes for unexpected next hops, prefixes, or session churn.
Public sources used
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-306: Credential and account abuse lookup
Authentication and credential weaknesses can make valid-account abuse and credential telemetry useful review starting points. 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 lookupCredential and access behavior lookup
The CVE wording references authentication or credential exposure, so valid-account and credential-access review may help. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-26928 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:L/UI:N/S:U/C:H/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:L/UI:N/S:U/C:H/I:N/A:H1.65.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.8MediumVector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.cyberark.com/resources/threat-research-blog/attacking-kubernetes-clusters-through-your-network-plumbing-part-2CVE reference · x_refsource_MISC
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.
Missing Authentication for Critical Function
Missing Authentication for Critical Function represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.