CVE-2020-36404: Keystone Engine 0.9.2 has an invalid free in llvm_ks::SmallVectorImpl<llvm_ks::MCFixup>::~SmallVectorImpl.

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HIGH 7.8DOWNGRADE

CVE-2020-36404 is a high-severity flaw (CVSS 7.8) affecting keystone. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Keystone Engine 0.9.2 has an invalid free in llvm_ks::SmallVectorImpl<llvm_ks::MCFixup>::~SmallVectorImpl.

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 35%)
CISA exploited list	No
Weakness	CWE-763
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 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 || rpm -q keystone || keystone --version

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

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

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

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

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-2020-36404?

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

Is CVE-2020-36404 being exploited?

CVE-2020-36404 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-2020-36404 affect?

CVE-2020-36404 affects keystone. Severity is high (CVSS 7.8). Keystone Engine 0.9.2 has an invalid free in llvm_ks::SmallVectorImpl<llvm_ks::MCFixup>::~SmallVectorImpl.

How urgent is CVE-2020-36404?

Priority 49/100. High severity; Public exploit reference

Related CVEs

CVE-2026-33551 LOW 3.5 UPGRADE An issue was discovered in OpenStack Keystone 14 through 26 before 26.1.1, 27.0.0, 28.0.0, and 29.0.0
CVE-2026-43001 HIGH 7.9 UPGRADE An issue was discovered in OpenStack Keystone before 29.0.2
CVE-2026-42999 MEDIUM 6.0 UPGRADE An issue was discovered in OpenStack Keystone before 29.0.2
CVE-2026-42998 MEDIUM 6.0 UPGRADE An issue was discovered in OpenStack Keystone before 29.0.2
CVE-2026-43000 MEDIUM 6.0 UPGRADE An issue was discovered in OpenStack Keystone before 29.0.2

References

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