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GHSA-c2pc-g5qf-rfrf

HighCVSS 7.5 / 10
Published Dec 9, 2024·Last modified Dec 9, 2024
Affected Components(0)

No affected components available

Description

Impact

Several polynomial time complexity issues in league/commonmark may lead to unbounded resource exhaustion and subsequent denial of service.

Malicious users could trigger that inefficient code with carefully crafted Markdown inputs that are specifically designed to ensure the worst-case performance is reached. Sending multiple such requests in parallel could tie up all available CPU resources and/or PHP-FPM processes, leading to denial of service for legitimate users.

Patches

These vulnerabilities have been patched in version 2.6.0. All users on older versions are highly encouraged to upgrade as soon as possible.

Workarounds

If you cannot upgrade, you may be able to mitigate the issues by:

  • Setting very low memory_limit and max_execution_time PHP configurations to prevent runaway resource usage
  • Implementing rate-limiting, bot protection, or other approaches to reduce the risk of simultaneous bad requests hitting your site
  • Limiting the size of inputs fed into this library (specifically the max length of each line)
  • Limiting the use of this library to trusted users

References

Most of these issues were discovered in other Markdown parsers. You can read more about them here:

  • https://github.com/commonmark/commonmark.js/issues/129
  • https://github.com/commonmark/commonmark.js/issues/157
  • https://github.com/commonmark/commonmark.js/issues/172
  • https://github.com/github/cmark-gfm/security/advisories/GHSA-r572-jvj2-3m8p
  • https://github.com/github/cmark-gfm/security/advisories/GHSA-24f7-9frr-5h2r
  • https://github.com/github/cmark-gfm/security/advisories/GHSA-29g3-96g3-jg6c
  • https://github.com/github/cmark-gfm/security/advisories/GHSA-r8vr-c48j-fcc5
  • https://github.com/github/cmark-gfm/security/advisories/GHSA-w4qg-3vf7-m9x5
  • https://github.com/github/cmark-gfm/security/advisories/GHSA-66g8-4hjf-77xh

For general information about this type of issue:

  • https://en.wikipedia.org/wiki/Time_complexity
  • https://cwe.mitre.org/data/definitions/407.html
Risk Scores
Base Score
7.5

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the availability of the system.

Threat Intelligence
6.9

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
N/A

Probability that this vulnerability will be exploited in the wild within the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

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High severity
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