CVE-2020-21726: OpenSNS v6.1.0 contains a blind SQL injection vulnerability in /Controller/ChinaCityController.class.php via t

This week

CRITICAL 9.8REMOTEDOWNGRADE

CVE-2020-21726 is a critical-severity flaw (CVSS 9.8) affecting opensns. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

OpenSNS v6.1.0 contains a blind SQL injection vulnerability in /Controller/ChinaCityController.class.php via the cid parameter.

Why this priority

Critical severity
Public exploit reference
Remotely exploitable, no login, no user action

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

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.3% (top 30%)
CISA exploited list	No
Weakness	CWE-89
Published	2021-10-07
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: opensns

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

Am I affected?

Timeline

2021-10-07 22:15 UTCPublished CVE record published
2026-06-17 03:03 UTCUpdated Record last modified

opensns opensns DOWNGRADE

Affected: 6.1.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.1.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 6.1.0 (Debian / Ubuntu)

apt-cache madison opensns sudo apt install opensns=<VERSION_BEFORE_6.1.0> sudo apt-mark hold opensns

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

dnf --showduplicates list opensns sudo dnf downgrade opensns-<VERSION_BEFORE_6.1.0> sudo dnf versionlock add opensns

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-2020-21726?

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

Is CVE-2020-21726 being exploited?

CVE-2020-21726 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-2020-21726 affect?

CVE-2020-21726 affects opensns. Severity is critical (CVSS 9.8). OpenSNS v6.1.0 contains a blind SQL injection vulnerability in /Controller/ChinaCityController.class.php via the cid parameter.

How urgent is CVE-2020-21726?

Priority 62/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

PHP vulnerabilities

Related CVEs

CVE-2020-21725 CRITICAL 9.8 DOWNGRADE OpenSNS v6.1.0 contains a blind SQL injection vulnerability in /Controller/ChinaCityController.class.php via t

References

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