Security readout for executives and security teams
Plain-English summary
An attacker who already has root control of a monitored machine could reuse previously valid TPM attestations, making the compromised system appear trustworthy to Keylime. This does not provide initial access; it weakens post-compromise detection. The issue is limited to push-model deployments.
Executive priority
Prioritize prompt remediation where Keylime push-mode attestation is relied upon to detect host compromise. Urgency is higher for sensitive systems or environments with suspected privileged intrusion. The root-access prerequisite limits general exposure, but successful abuse could undermine confidence in a core security control.
Technical view
The Keylime verifier uses a fixed challenge nonce for TPM quotes instead of a cryptographically random value. Because the challenge is predictable, a root-level attacker can collect valid quotes before or during compromise and replay them later. The flaw has CVSS 3.1 score 6.3 and affects attestation integrity in the push model.
Likely exposure
Exposure is limited to Keylime push-model deployments. The bundle identifies affected Keylime packages on RHEL 9 and RHEL 10, including 0:7.14.1-5.el10_2.1 on RHEL 10. The RHEL 9 version range is unspecified. Keylime 7.14.0 is separately marked default unaffected, leaving broader non-Red Hat scope unclear.
Exploitation context
Exploitation requires local access and root privileges on an enrolled monitored machine; no user interaction is required. The attacker must obtain reusable valid TPM quotes. The CVE is not listed in KEV, and the supplied sources provide no evidence of active exploitation.
Researcher notes
The weakness is a freshness failure classified as CWE-1241: predictable attestation challenges permit replay of previously valid evidence. Scope data is incomplete: RHEL 9 lacks an affected version range, and the bundle does not identify fixed versions. Testing should focus on nonce uniqueness without publishing replay procedures or payloads.
Mitigation direction
- Review RHSA-2026:28582 and apply the vendor-supported update or mitigation it prescribes.
- Prioritize remediation on systems using Keylime's push model.
- Strengthen privileged-access controls and investigate suspected root compromise on enrolled agents.
- Consult the relevant vendor for non-Red Hat deployments; fixed versions are not identified in the bundle.
Validation and detection
- Inventory Keylime packages on RHEL 9 and RHEL 10 systems.
- Confirm whether each deployment uses push-model attestation.
- Compare installed package builds and remediation status with RHSA-2026:28582.
- Review attestation records for suspicious repetition, recognizing replayed quotes may appear valid.
- Verify corrected deployments no longer rely on a fixed TPM quote challenge nonce.
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-1241: 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-2026-6420 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
- 6.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L
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.
SSVC decision data
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:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L0.85.5redhatVulnerability scoring details
Base CVSS 3.1 score
6.3MediumVector: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L
Vulnerability timeline
Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.
- Source timelineredhat
Reported to Red Hat.
- CVE reservedCVE Program
The CVE ID was reserved by the assigning CNA.
- Source timelineredhat
Made public.
- CVE publishedCVE Program
The CVE record was published.
- CVE updatedCVE Program
The CVE record metadata indicates this as the latest update time.
ADP provider summaries
Source materials
- CVE List V5 sourceCVE List V5
- RHSA-2026:28582CVE reference, redhat · vendor-advisory, x_refsource_REDHAT
- https://access.redhat.com/security/cve/CVE-2026-6420CVE reference, redhat · vdb-entry, x_refsource_REDHAT
- RHBZ#2458889CVE reference, redhat · issue-tracking, x_refsource_REDHAT
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.
Use of Predictable Algorithm in Random Number Generator
Use of Predictable Algorithm in Random Number Generator represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.