How severe is CVE-2021-1104?

CVE-2021-1104 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-1104 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-1104?

CVE-2021-1104 affects Risc-v Instruction Set Manual. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-1104?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-1104 published?

CVE-2021-1104 was published on 2021-08-13 and last updated on 2026-06-17.

CVE-2021-1104

CVE-2021-1104 is a critical-severity vulnerability in Risc-v Instruction Set Manual with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-908.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 7.5
EPSS exploit prediction: 2% (74th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-908
Affected product: Risc-v Instruction Set Manual
Published: 2021-08-13
Last modified: 2026-06-17

Description

The RISC-V Instruction Set Manual contains a documented ambiguity for the Machine Trap Vector Base Address (MTVEC) register that may lead to a vulnerability due to the initial state of the register not being defined, potentially leading to information disclosure, data tampering and denial of service.

Frequently asked questions

What is CVE-2021-1104?: The RISC-V Instruction Set Manual contains a documented ambiguity for the Machine Trap Vector Base Address (MTVEC) register that may lead to a vulnerability due to the initial state of the register not being defined, potentially leading to information disclosure, data tampering and denial of service.
How severe is CVE-2021-1104?: CVE-2021-1104 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-1104 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-1104?: CVE-2021-1104 affects Risc-v Instruction Set Manual. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-1104?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-1104 published?: CVE-2021-1104 was published on 2021-08-13 and last updated on 2026-06-17.

References

https://riscv.org/news/2021/08/video-glitching-risc-v-chips-mtvec-corruption-for-hardening-isa-adam-zabrocki-and-alex-matrosov-def-con-29/

Affected products (1)

cpe:2.3:a:risc-v:instruction_set_manual:*:*:*:*:*:*:*:*

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