CVE-2020-9434: openssl_x509_check_ip_asc in lua-openssl 0.7.7-1 mishandles X.509 certificate validation because it uses lua_p

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CRITICAL 9.1REMOTEWATCHLISTDOWNGRADE

CVE-2020-9434 is a critical-severity flaw (CVSS 9.1) affecting lua-openssl. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

openssl_x509_check_ip_asc in lua-openssl 0.7.7-1 mishandles X.509 certificate validation because it uses lua_pushboolean for certain non-boolean return values.

Why this priority

Critical severity
Remotely exploitable, no login, no user action
On your watchlist

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

Risk facts

CVSS score	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.8% (top 42%)
CISA exploited list	No
Weakness	CWE-295
Published	2020-02-27
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: lua-openssl project

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

Am I affected?

Timeline

2020-02-27 23:15 UTCPublished CVE record published
2026-06-17 03:27 UTCUpdated Record last modified

lua-openssl project lua-openssl DOWNGRADE

Affected: 0.7.7-1

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.7.7-1

1. Check installed version

apt-cache policy lua-openssl || rpm -q lua-openssl || lua-openssl --version

2. No fixed release: DOWNGRADE to a release before 0.7.7-1 (Debian / Ubuntu)

apt-cache madison lua-openssl sudo apt install lua-openssl=<VERSION_BEFORE_0.7.7-1> sudo apt-mark hold lua-openssl

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

dnf --showduplicates list lua-openssl sudo dnf downgrade lua-openssl-<VERSION_BEFORE_0.7.7-1> sudo dnf versionlock add lua-openssl

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-2020-9434?

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

Is CVE-2020-9434 being exploited?

CVE-2020-9434 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-2020-9434 affect?

CVE-2020-9434 affects lua-openssl. Severity is critical (CVSS 9.1). openssl_x509_check_ip_asc in lua-openssl 0.7.7-1 mishandles X.509 certificate validation because it uses lua_pushboolean for certain non-boolean return values.

How urgent is CVE-2020-9434?

Priority 56/100. Critical severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

OpenSSL vulnerabilities

Related CVEs

CVE-2020-9433 CRITICAL 9.1 DOWNGRADE openssl_x509_check_email in lua-openssl 0.7.7-1 mishandles X.509 certificate validation because it uses lua_pu
CVE-2020-9432 CRITICAL 9.1 DOWNGRADE openssl_x509_check_host in lua-openssl 0.7.7-1 mishandles X.509 certificate validation because it uses lua_pus

References

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