CVE-2020-36402: Solidity 0.7.5 has a stack-use-after-return issue in smtutil::CHCSmtLib2Interface::querySolver

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HIGH 7.8DOWNGRADE

CVE-2020-36402 is a high-severity flaw (CVSS 7.8) affecting solidity. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Solidity 0.7.5 has a stack-use-after-return issue in smtutil::CHCSmtLib2Interface::querySolver. NOTE: c39a5e2b7a3fabbf687f53a2823fc087be6c1a7e is cited in the OSV "fixed" field but does not have a code change.

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	1.0% (top 39%)
CISA exploited list	No
Weakness	CWE-787
Published	2021-07-01
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: soliditylang

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

soliditylang solidity DOWNGRADE

Affected: 0.7.5

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.7.5

1. Check installed version

apt-cache policy solidity || rpm -q solidity || solidity --version

2. No fixed release: DOWNGRADE to a release before 0.7.5 (Debian / Ubuntu)

apt-cache madison solidity sudo apt install solidity=<VERSION_BEFORE_0.7.5> sudo apt-mark hold solidity

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

dnf --showduplicates list solidity sudo dnf downgrade solidity-<VERSION_BEFORE_0.7.5> sudo dnf versionlock add solidity

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-2020-36402?

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

Is CVE-2020-36402 being exploited?

CVE-2020-36402 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-2020-36402 affect?

CVE-2020-36402 affects solidity. Severity is high (CVSS 7.8). Solidity 0.7.5 has a stack-use-after-return issue in smtutil::CHCSmtLib2Interface::querySolver. NOTE: c39a5e2b7a3fabbf687f53a2823fc087be6c1a7e is cited in the OSV "fixed" field but does not have a code change.

How urgent is CVE-2020-36402?

Priority 48/100. High severity; Public exploit reference

Related CVEs

CVE-2022-33069 MEDIUM 5.5 DOWNGRADE Ethereum Solidity v0.8.14 contains an assertion failure via SMTEncoder::indexOrMemberAssignment() at SMTEncode

References

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