CVE-2021-38512: An issue was discovered in the actix-http crate before 3.0.0-beta.9 for Rust

Q: How do I fix CVE-2021-38512?

actix-http: upgrade to 3.0.0; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2021-38512 being exploited?

CVE-2021-38512 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-38512 affect?

CVE-2021-38512 affects actix-http, fedora. Severity is high (CVSS 7.5). An issue was discovered in the actix-http crate before 3.0.0-beta.9 for Rust. HTTP/1 request smuggling (aka HRS) can occur, potentially leading to credential disclosure.

Q: How urgent is CVE-2021-38512?

Priority 56/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

This week

HIGH 7.5REMOTEUPGRADEMITIGATE

CVE-2021-38512 is a high-severity flaw (CVSS 7.5) affecting actix-http, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in the actix-http crate before 3.0.0-beta.9 for Rust. HTTP/1 request smuggling (aka HRS) can occur, potentially leading to credential disclosure.

Why this priority

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

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	1.8% (top 21%)
CISA exploited list	No
Weakness	CWE-444
Published	2021-08-10
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: actix · fedoraproject

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

Am I affected?

Timeline

2021-08-10 23:15 UTCPublished CVE record published
2026-06-17 04:02 UTCUpdated Record last modified

actix actix-http UPGRADE

Affected: < 3.0.0 · 3.0.0 · 3.0.0 beta1 · 3.0.0 beta2 · 3.0.0 beta3 · 3.0.0 beta4 · 3.0.0 beta5 · 3.0.0 beta6

Fixed in: 3.0.0

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to 3.0.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade actix-http

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade actix-http

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

fedoraproject fedora MITIGATE

Affected: 34

Fixed in: no fixed release known

Safe to downgrade to: a release before 34

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2021-38512?

actix-http: upgrade to 3.0.0; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-38512 being exploited?

CVE-2021-38512 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-2021-38512 affect?

CVE-2021-38512 affects actix-http, fedora. Severity is high (CVSS 7.5). An issue was discovered in the actix-http crate before 3.0.0-beta.9 for Rust. HTTP/1 request smuggling (aka HRS) can occur, potentially leading to credential disclosure.

How urgent is CVE-2021-38512?

Priority 56/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2020-35901 HIGH 7.5 UPGRADE An issue was discovered in the actix-http crate before 2.0.0-alpha.1 for Rust

References

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