CVE-2020-21699: The web server Tengine 2.2.2 developed in the Nginx version from 0.5.6 thru 1.13.2 is vulnerable to an integer

This month

HIGH 7.5REMOTEWATCHLISTDOWNGRADE

CVE-2020-21699 is a high-severity flaw (CVSS 7.5) affecting tengine. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The web server Tengine 2.2.2 developed in the Nginx version from 0.5.6 thru 1.13.2 is vulnerable to an integer overflow vulnerability in the nginx range filter module, resulting in the leakage of potentially sensitive information triggered by specially crafted requests.

Why this priority

High 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	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.8% (top 43%)
CISA exploited list	No
Weakness	CWE-190
Published	2023-08-22
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: alibaba

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

Am I affected?

Timeline

2023-08-22 19:16 UTCPublished CVE record published
2026-06-17 03:03 UTCUpdated Record last modified

alibaba tengine DOWNGRADE

Affected: 2.2.2

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.2.2

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 2.2.2 (Debian / Ubuntu)

apt-cache madison tengine sudo apt install tengine=<VERSION_BEFORE_2.2.2> sudo apt-mark hold tengine

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

dnf --showduplicates list tengine sudo dnf downgrade tengine-<VERSION_BEFORE_2.2.2> sudo dnf versionlock add tengine

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-2020-21699?

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

Is CVE-2020-21699 being exploited?

CVE-2020-21699 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-2020-21699 affect?

CVE-2020-21699 affects tengine. Severity is high (CVSS 7.5). The web server Tengine 2.2.2 developed in the Nginx version from 0.5.6 thru 1.13.2 is vulnerable to an integer overflow vulnerability in the nginx range filter module, resulting in the leakage of potentially sensitive information triggered

How urgent is CVE-2020-21699?

Priority 50/100. High severity; Remotely exploitable, no login, no user action; On your watchlist

Software pages

nginx vulnerabilities

References

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