CVE-2026-29644: Access Control Flaw (CVSS 5.3)

Description

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.

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CVSS v3.1 Score

5.3

MEDIUM

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

EPSS — Exploit Prediction

0.0001

Probability of exploitation

0.02%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-284 CWE-284

References

Other References

https://docs.riscv.org/reference/isa/priv/priv-csrs.html https://github.com/OpenXiangShan/XiangShan/commit/2b1f9796aa98597e5eeac32e5bb1418496987ca4 https://github.com/OpenXiangShan/XiangShan/commit/edb1dfaf7d290ae99724594507dc46c2c2125384 https://github.com/OpenXiangShan/XiangShan/issues/3959 https://xiangshan-doc-test.readthedocs.io/next/memory/mmu/pmp_pma/ https://github.com/OpenXiangShan/XiangShan/issues/3959

Frequently Asked Questions

What is CVE-2026-29644? +

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. It has a CVSS v3.1 base score of 5.3 (MEDIUM).

How severe is CVE-2026-29644? +

CVE-2026-29644 has a CVSS v3.1 score of 5.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0001, placing it in the 0th percentile for exploitation probability.

How do I check if I'm vulnerable to CVE-2026-29644? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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