CVE-2026-45300: The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously

Routine

HIGH 7.4UPGRADE

CVE-2026-45300 is a high-severity flaw (CVSS 7.4) affecting async-http-client. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. Versions on the 2.x branch prior to 2.15.0 and the 3.x branch prior to 3.0.10 leak `Cookie` headers to cross-origin redirect targets. When following a redirect to a different origin, the `propagatedHeaders()` method in `Redirect30xInterceptor.java` strips `Authorization` and `Proxy-Authorization` headers but does n

Why this priority

High severity
Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	7.4 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.4% (top 66%)
CISA exploited list	No
Weakness	CWE-200
Published	2026-06-05
Last modified	2026-07-23

Publisher (CNA): GitHub, Inc. · Vendor: asynchttpclient project

Last updated 2026-07-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-06-05 20:17 UTCPublished CVE record published
2026-07-23 07:10 UTCUpdated Record last modified

asynchttpclient project async-http-client UPGRADE

Affected: >= 2.0.0 and < 2.15.0 · >= 3.0.0 and < 3.0.10

Fixed in: 2.15.0, 3.0.10

Safe to downgrade to: a release before 2.0.0

1. Check installed version

apt-cache policy async-http-client || rpm -q async-http-client || async-http-client --version

2. UPGRADE to 2.15.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade async-http-client

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade async-http-client

Note

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

3. If no update is available yet, DOWNGRADE to a release before 2.0.0 (Debian / Ubuntu)

apt-cache madison async-http-client sudo apt install async-http-client=<VERSION_BEFORE_2.0.0> sudo apt-mark hold async-http-client

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list async-http-client sudo dnf downgrade async-http-client-<VERSION_BEFORE_2.0.0> sudo dnf versionlock add async-http-client

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-2026-45300?

async-http-client: upgrade to 2.15.0, 3.0.10. Exact commands for each OS are on this page.

Is CVE-2026-45300 being exploited?

CVE-2026-45300 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-2026-45300 affect?

CVE-2026-45300 affects async-http-client. Severity is high (CVSS 7.4). The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. Versions on the 2.x branch prior to 2.15.0 and the 3.x branch prior to 3.0.10 leak `Cookie` headers to cro

How urgent is CVE-2026-45300?

Priority 39/100. High severity; Public exploit reference

Software pages

Java vulnerabilities

References

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