How severe is CVE-2026-45300?

CVE-2026-45300 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-45300 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-45300?

CVE-2026-45300 affects Asynchttpclient Project Async-http-client. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-45300?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-45300 have an EU (EUVD) identifier?

Yes. CVE-2026-45300 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-34910.

When was CVE-2026-45300 published?

CVE-2026-45300 was published on 2026-06-05 and last updated on 2026-06-17.

CVE-2026-45300

CVE-2026-45300 is a high-severity vulnerability in Asynchttpclient Project Async-http-client with a CVSS 3.x base score of 7.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-200.

Key facts

Severity: High (CVSS 3.x base score 7.4)
EPSS exploit prediction: 0% (24th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-34910
Weakness: CWE-200
Affected product: Asynchttpclient Project Async-http-client
Published: 2026-06-05
Last modified: 2026-06-17

Description

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 not strip the `Cookie` header, causing session cookies and other sensitive cookie values to be sent to attacker-controlled servers. Versions 2.15.0 and 3.0.10 patch the issue.

Frequently asked questions

What is CVE-2026-45300?: 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 not strip the `Cookie` header, causing session cookies and other sensitive cookie values to be sent to attacker-controlled servers. Versions 2.15.0 and 3.0.10 patch the issue.
How severe is CVE-2026-45300?: CVE-2026-45300 has a CVSS 3.x base score of 7.4, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-45300 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (24th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-45300?: CVE-2026-45300 affects Asynchttpclient Project Async-http-client. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-45300?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-45300 have an EU (EUVD) identifier?: Yes. CVE-2026-45300 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-34910.
When was CVE-2026-45300 published?: CVE-2026-45300 was published on 2026-06-05 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:asynchttpclient_project:async-http-client:*:*:*:*:*:*:*:*

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