CVE-2020-21574: Buffer overflow vulnerability in YotsuyaNight c-http v0.1.0, allows attackers to cause a denial of service via

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HIGH 7.5REMOTEDOWNGRADE

CVE-2020-21574 is a high-severity flaw (CVSS 7.5) affecting c-http. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Buffer overflow vulnerability in YotsuyaNight c-http v0.1.0, allows attackers to cause a denial of service via a long url request which is passed to the delimitedread function.

Why this priority

High 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	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.0% (top 38%)
CISA exploited list	No
Weakness	CWE-120
Published	2021-11-02
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: c-http project

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

Am I affected?

Timeline

2021-11-02 18:15 UTCPublished CVE record published
2026-06-17 03:03 UTCUpdated Record last modified

c-http project c-http DOWNGRADE

Affected: 0.1.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.1.0

1. Check installed version

apt-cache policy c-http || rpm -q c-http || c-http --version

2. No fixed release: DOWNGRADE to a release before 0.1.0 (Debian / Ubuntu)

apt-cache madison c-http sudo apt install c-http=<VERSION_BEFORE_0.1.0> sudo apt-mark hold c-http

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

dnf --showduplicates list c-http sudo dnf downgrade c-http-<VERSION_BEFORE_0.1.0> sudo dnf versionlock add c-http

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-2020-21574?

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

Is CVE-2020-21574 being exploited?

CVE-2020-21574 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-2020-21574 affect?

CVE-2020-21574 affects c-http. Severity is high (CVSS 7.5). Buffer overflow vulnerability in YotsuyaNight c-http v0.1.0, allows attackers to cause a denial of service via a long url request which is passed to the delimitedread function.

How urgent is CVE-2020-21574?

Priority 52/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

References

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