Vulnerability in react/http (CVE-2026-84997)
Summary
Vulnerability in react/http (CVE-2026-84997). Risk of unauthorized operations or information disclosure. Exploitable via ChunkedDecoder. Mitigation: upgrade to 1.11.1 or later.
Original description
The description as published by the source.
Summary
A malformed HTTP message using Transfer-Encoding: chunked can drive React\Http\Io\ChunkedDecoder into an infinite loop, pegging a CPU core and freezing the event loop. Because ReactPHP is single-threaded, one such message stalls the entire process for every client until it is killed.
Both directions are affected. ChunkedDecoder decodes chunked request bodies for React\Http\HttpServer and chunked response bodies for React\Http\Browser, so a server can be attacked by a malicious client and a client can be attacked by a malicious or compromised server.
Details
ChunkedDecoder::handleData() loops while ($this->buffer !== '') and relies on the buffer shrinking each iteration. Two states leave the buffer unchanged while the loop condition stays true.
Terminal-chunk trailer. After the terminating 0 chunk, any remaining buffer is treated as trailer data to skip:
} elseif ($this->chunkSize === 0) {
$this->buffer = (string)\substr($this->buffer, $positionCrlf);
}
When the trailer holds no CRLF yet, strpos() returns false, PHP coerces that to 0 in substr(), and the buffer is never advanced. Neither the error guard (which requires a non-zero chunk size) nor the wait guard (which requires fewer than two bytes remaining) can fire, so the loop re-enters with identical state.
Off-by-one after a completed chunk. Once a non-terminal chunk has been fully transferred, the "chunk does not end with a CRLF" error guard re…
Source: NIST National Vulnerability Database NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-84997 has been found in react/http.
Attackers can target a specific entry point like ChunkedDecoder over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade react/http to 1.11.1 or later.
If unsure, ask your IT team or search "react/http CVE-2026-84997" on the vendor's site.
CVE-2026-84997 (react/http) — CWE-835 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: ChunkedDecoder / false / Browser
Patched: 1.11.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-835) exists in react/http. Attackers reach the vulnerable code path via ChunkedDecoder without authentication.
Check the vendor advisory for the affected versions of react/http. Attack surface: ChunkedDecoder / false / Browser.
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure.
Update to 1.11.1.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'react/http' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 'react/http' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
react/httpを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade react/http to 1.11.1ステージング環境で 1.11.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- web github.com
- web github.com
- web github.com
- web nvd.nist.gov
- web github.com
- web github.com