Security readout for executives and security teams
Plain-English summary
CVE-2021-22556 is a Fuchsia kernel flaw where a local attacker who can already run code could interfere with memory pages they do not own. That can let user-space code influence kernel memory, which raises privilege and data-protection concerns despite the medium CVSS score.
Executive priority
Treat as a focused platform update issue, not an internet-wide emergency. Prioritize if Fuchsia is deployed where local code execution by users, apps, or attackers is plausible. The main business concern is kernel memory compromise after initial local execution.
Technical view
The issue is an integer overflow in the Fuchsia kernel tied to memory cache invalidation operations. The CVSS vector indicates local access, high attack complexity, low privileges, no user interaction, high confidentiality impact, low integrity impact, and no availability impact. Google recommends upgrading to kernel version 4.1 or later.
Likely exposure
Exposure appears limited to systems running affected Google Fuchsia kernel versions. The source bundle does not identify exact vulnerable versions or CPEs. Risk is most relevant where untrusted or compromised local code can execute on Fuchsia-based devices or environments.
Exploitation context
The sources describe exploitation as requiring existing code execution and local, low-privileged access. CISA KEV status is false in the bundle, and no cited source supports active exploitation. No remote attack path is documented in the supplied evidence.
Researcher notes
Evidence is incomplete for exact affected versions, exploit maturity, and productized device exposure. The public description points to an integer overflow enabling unauthorized cache invalidation against non-owned pages. Validate against Fuchsia build history and the referenced code review rather than assuming broad Google product impact.
Mitigation direction
- Upgrade Fuchsia kernel to version 4.1 or beyond.
- Review Google Fuchsia release notes and vendor guidance for applicable build details.
- Limit execution of untrusted local code on Fuchsia systems.
- Prioritize updates on shared, developer, or exposed Fuchsia environments.
Validation and detection
- Inventory Fuchsia systems and record kernel or platform build versions.
- Confirm whether deployed builds include the referenced Fuchsia security fix.
- Check vulnerability management data for CVE-2021-22556 matches.
- Document systems already running kernel version 4.1 or later.
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-190: Exact CWE lookup
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Open ATT&CK lookupExecution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-22556 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
- 5.3 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N
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:L/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N14.2Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.3MediumVector: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://fuchsia.dev/whats-new/release-notes/f4-1CVE reference · x_refsource_MISC
- https://fuchsia-review.googlesource.com/c/fuchsia/+/570881CVE 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.