CVE-2020-36405: Keystone Engine 0.9.2 has a use-after-free in llvm_ks::X86Operand::getToken.

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HIGH 7.8DOWNGRADE

CVE-2020-36405 is a high-severity flaw (CVSS 7.8) affecting keystone engine. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Keystone Engine 0.9.2 has a use-after-free in llvm_ks::X86Operand::getToken.

Why this priority

High severity
Public exploit reference

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.8 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.1% (top 34%)
CISA exploited list	No
Weakness	CWE-416
Published	2021-07-01
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: keystone-engine

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-07-01 03:15 UTCPublished CVE record published
2026-06-17 03:15 UTCUpdated Record last modified

keystone-engine keystone engine DOWNGRADE

Affected: 0.9.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.9.2

1. Check installed version

apt-cache policy keystone-engine || rpm -q keystone-engine || keystone-engine --version

2. No fixed release: DOWNGRADE to a release before 0.9.2 (Debian / Ubuntu)

apt-cache madison keystone-engine sudo apt install keystone-engine=<VERSION_BEFORE_0.9.2> sudo apt-mark hold keystone-engine

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list keystone-engine sudo dnf downgrade keystone-engine-<VERSION_BEFORE_0.9.2> sudo dnf versionlock add keystone-engine

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2020-36405?

keystone engine: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2020-36405 being exploited?

CVE-2020-36405 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2020-36405 affect?

CVE-2020-36405 affects keystone engine. Severity is high (CVSS 7.8). Keystone Engine 0.9.2 has a use-after-free in llvm_ks::X86Operand::getToken.

How urgent is CVE-2020-36405?

Priority 49/100. High severity; Public exploit reference

References

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