CVE-2026-107282: AsyncHttpClient: Replay to a different host sends the original host request and credentials to the new host

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.2%, percentile 8: FIRST’s model estimates a 0.2% chance of exploitation activity in the next 30 days, higher than 8% of all scored CVEs (low). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes org.asynchttpclient:async-http-client (Maven) >= 3.0.0, <= 3.0.12, fixed in 3.0.13; org.asynchttpclient:async-http-client (Maven) >= 2.0.0, <= 2.16.0, fixed in 2.16.1. Check your lockfile, including transitive dependencies.

What it is

The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. Prior to 3.0.13 and 2.16.1, cross-host request replay updates the current request but leaves the target request and related proxy context pointing at the original origin. Connection-pool selection, CONNECT handling, realm selection, and TLS setup can consequently send the original host's path, Host header, Authorization credentials, or plaintext request to the replay destination. Documented ResponseFilter failover and retry paths can trigger the replay. This issue is fixed in versions 3.0.13 and 2.16.1.

From the GitHub advisory

Impact When a request is replayed onto a different host, the client updates only the current request and leaves the target request pointing at the original host. Four consumers read that stale value, and each one sends the first host's request, credentials, or both to the second host.

A replay happens through documented, ordinary features: a ResponseFilter that returns a different request, which is the supported failover pattern, and the IOException retry path. The attacker does not need to induce the replay; an application that uses failover produces it by design.

The socket to host B is filed in the connection pool under host A's key. A later request the application addresses to A is served over the connection to B, and A's Authorization header goes to B. Over a CONNECT tunnel, the client tunnels to B and negotiates TLS with B correctly, then writes A's request into that tunnel. B receives A's path, A's Host, and A's Authorization. TLS does not protect against this, because the handshake really is with B, so no certificate mismatch occurs. The replay reuses the original realm, so A's credentials are regenerated onto a replay request that carries no realm of its own. The cross-origin redirect path strips realms for exactly this reason; the replay path never did. The stale value also decides whether TLS is used at all. When the original request was http:// and the replay is https://, no SSL handler is installed and the replayed request, credentials included, is written in cleartext.

Affected versions 3.x: up to and including 3.0.12 2.x: up to and including 2.16.0

Both lines are affected identically. This is long-standing behaviour, not a recent regression.

Weakness type: CWE-319, CWE-441, CWE-522.

Product: org.asynchttpclient:async-http-client (Maven) · Assigned by: GitHub_M · Published: 2026-10-07

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: high (needs special conditions)
• Attack requirements: present (depends on deployment conditions)
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.19% probability of exploitation activity in the next 30 days; percentile 8.

Timeline

• 2026-10-07 — CVE record published by GitHub_M
• 2026-10-08 — GitHub-reviewed advisory GHSA-jmqq-x5g9-9p2w published (critical)
• 2026-10-10 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vulnerability records

1. GitHub Advisory GHSA-jmqq-x5g9-9p2w github.com
2. CVE.org record CVE-2026-107282 cve.org
3. NVD entry CVE-2026-107282 nvd.nist.gov

Other references from the CVE record and advisory

1. github.com github.com
2. github.com github.com
3. github.com github.com
4. github.com github.com
5. github.com github.com

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