dbcve.org
Improper Access ControlWeakness · CWE-284

CVE-2026-29644

MEDIUM · 5.3 CVSS v3.1 Published 2026-04-21
Patch available
A vendor patch is available. No clean upgrade release — apply the published patch.
See remediation →
55/100
Remediation priority · Elevated
Zero-click Patch available

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 · unedited
XiangShan (open-source high-performance RISC-V processor) commit edb1dfaf7d290ae99724594507dc46c2c2125384 (2024-11-28) has improper gating of its distributed CSR write-enable path, allowing illegal CSR write attempts to alter custom PMA (Physical Memory Attribute) CSR state. Though the RISC-V privileged specification requires an illegal-instruction exception for non-existent/illegal CSR accesses, affected XiangShan versions may still propagate such writes to replicated PMA configuration state. Local attackers able to execute code on the core (privilege context depends on system integration) can exploit this to tamper with memory-attribute enforcement, potentially leading to privilege escalation, information disclosure, or denial of service depending on how PMA enforces platform security and isolation boundaries.

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
How this class of weakness works · CWE-284

The application fails to correctly restrict what a user can do or reach, so functions or resources are available to people who should not have them. Attackers simply probe for the paths where the check is missing or wrong. The fix is to enforce access-control decisions consistently on every request, evaluated against the acting user rather than assumed from context.

General guidance for the improper access control class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

CVSS 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
Low
User interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
Low
Availability
Low

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L

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 · scoped
Patch available Apply the vendor patch
Vendor patch github.com →
Recommended fix Moderate confidence

Apply vendor patch commit 2b1f9796aa98597e5eeac32e5bb1418496987ca4 or update to a release branch/commit after this fix

  1. 1. Navigate to the XiangShan repository: https://github.com/OpenXiangShan/XiangShan
  2. 2. Locate the commit edb1dfaf7d290ae99724594507dc46c2c2125384 (the vulnerable commit from 2024-11-28) in the git history
  3. 3. Apply the vendor patch from commit 2b1f9796aa98597e5eeac32e5bb1418496987ca4 which fixes the CSR write-enable path gating issue
  4. 4. Verify the patch addresses the improper access control by reviewing the diff - the fix should properly gate the distributed CSR write-enable path to prevent illegal CSR writes from altering custom PMA CSR state
  5. 5. Rebuild the processor after applying the patch
  6. 6. Test that illegal CSR access attempts now correctly trigger illegal-instruction exceptions as required by the RISC-V privileged specification

Generated from the published advisory — verify against the referenced sources before acting.

We can apply and verify the patch for your build — typical engagement from $1,600. Get the patch applied

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2026-29644 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-29644 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data