CVE-2020-36431: Unicorn Engine 1.0.2 has an out-of-bounds write in helper_wfe_arm.

Routine

MEDIUM 5.5DOWNGRADE

CVE-2020-36431 is a medium-severity flaw (CVSS 5.5) affecting unicorn engine. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Unicorn Engine 1.0.2 has an out-of-bounds write in helper_wfe_arm.

Why this priority

No elevated risk signals yet

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

Risk facts

CVSS score	5.5 (Medium)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.3% (top 80%)
CISA exploited list	No
Weakness	CWE-787
Published	2021-07-20
Last modified	2026-06-17

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

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

Am I affected?

Timeline

2021-07-20 07:15 UTCPublished CVE record published
2026-06-17 03:15 UTCUpdated Record last modified

unicorn-engine unicorn engine DOWNGRADE

Affected: 1.0.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 1.0.2

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 1.0.2 (Debian / Ubuntu)

apt-cache madison unicorn-engine sudo apt install unicorn-engine=<VERSION_BEFORE_1.0.2> sudo apt-mark hold unicorn-engine

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

dnf --showduplicates list unicorn-engine sudo dnf downgrade unicorn-engine-<VERSION_BEFORE_1.0.2> sudo dnf versionlock add unicorn-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-2020-36431?

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

Is CVE-2020-36431 being exploited?

CVE-2020-36431 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-2020-36431 affect?

CVE-2020-36431 affects unicorn engine. Severity is medium (CVSS 5.5). Unicorn Engine 1.0.2 has an out-of-bounds write in helper_wfe_arm.

How urgent is CVE-2020-36431?

Priority 24/100. No elevated risk signals yet.

Related CVEs

CVE-2022-29695 HIGH 7.5 UPGRADE Unicorn Engine v2.0.0-rc7 contains memory leaks caused by an incomplete unicorn engine initialization.
CVE-2022-29694 HIGH 7.5 UPGRADE Unicorn Engine v2.0.0-rc7 and below was discovered to contain a NULL pointer dereference via qemu_ram_free.
CVE-2022-29693 HIGH 7.5 UPGRADE Unicorn Engine v2.0.0-rc7 and below was discovered to contain a memory leak via the function uc_close at /my/u
CVE-2022-29692 HIGH 7.8 DOWNGRADE Unicorn Engine v1.0.3 was discovered to contain a use-after-free vulnerability via the hook function.
CVE-2021-44078 HIGH 8.1 UPGRADE An issue was discovered in split_region in uc.c in Unicorn Engine before 2.0.0-rc5

References

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