Improperly Controlled Sequential Memory Allocation Affecting guzzlehttp/guzzle package, versions <7.15.1
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
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Test your applications- Snyk IDSNYK-PHP-GUZZLEHTTPGUZZLE-18306780
- published25 Jul 2026
- disclosed20 Jul 2026
- creditUnknown
Introduced: 20 Jul 2026
CVE-2026-67353 (opens in a new tab)How to fix?
Upgrade guzzlehttp/guzzle to version 7.15.1 or higher.
Overview
Affected versions of this package are vulnerable to Improperly Controlled Sequential Memory Allocation via the CookieJar process. An attacker can exhaust system memory and cause service disruption by sending a large number of oversized Set-Cookie headers in responses, which are then stored and included in subsequent requests without proper limits. This can lead to increased memory usage, processing delays, and potential request failures when header size limits are exceeded in downstream systems. This is only exploitable if built-in cookie support is enabled, attacker-controlled responses are received, and the same jar is retained or reused.
Workaround
This vulnerability can be mitigated by not enabling a shared built-in cookie jar for requests to untrusted origins, using separate jars per host or trust boundary, disabling cookie handling for untrusted requests, discarding or clearing a jar after receiving an untrusted response, or providing a custom CookieJarInterface implementation that enforces suitable limits.