Excessive Platform Resource Consumption within a Loop Affecting league/commonmark package, versions >=0.6.0, <2.9.0
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-LEAGUECOMMONMARK-18600655
- published9 Aug 2026
- disclosed6 Aug 2026
- creditUnknown
Introduced: 6 Aug 2026
NewCVE-2026-71488 (opens in a new tab)How to fix?
Upgrade league/commonmark to version 2.9.0 or higher.
Overview
league/commonmark is a PHP-based Markdown parser which supports the full CommonMark spec. It is based on the CommonMark JS reference implementation.
Affected versions of this package are vulnerable to Excessive Platform Resource Consumption within a Loop through the Markdown parsing process. An attacker can exhaust CPU resources and cause service unavailability by submitting specially crafted Markdown input with long lines, non-ASCII characters, or repeated URL-like prefixes. This is only exploitable if untrusted Markdown input is processed.
Workaround
This vulnerability can be mitigated by rejecting or truncating inputs with excessively long individual lines before parsing, enforcing per-line and total request-size limits, restricting conversion to trusted users, applying strict execution-time limits, rate-limiting requests, limiting concurrent conversions, or disabling the AutolinkExtension and avoiding GithubFlavoredMarkdownExtension.