rustsec-2022-0013
Vulnerability from osv_rustsec
Published
2022-03-08 12:00
Modified
2023-06-13 13:10
Summary
Regexes with large repetitions on empty sub-expressions take a very long time to parse
Details

The Rust Security Response WG was notified that the regex crate did not properly limit the complexity of the regular expressions (regex) it parses. An attacker could use this security issue to perform a denial of service, by sending a specially crafted regex to a service accepting untrusted regexes. No known vulnerability is present when parsing untrusted input with trusted regexes.

This issue has been assigned CVE-2022-24713. The severity of this vulnerability is "high" when the regex crate is used to parse untrusted regexes. Other uses of the regex crate are not affected by this vulnerability.

Overview

The regex crate features built-in mitigations to prevent denial of service attacks caused by untrusted regexes, or untrusted input matched by trusted regexes. Those (tunable) mitigations already provide sane defaults to prevent attacks. This guarantee is documented and it's considered part of the crate's API.

Unfortunately a bug was discovered in the mitigations designed to prevent untrusted regexes to take an arbitrary amount of time during parsing, and it's possible to craft regexes that bypass such mitigations. This makes it possible to perform denial of service attacks by sending specially crafted regexes to services accepting user-controlled, untrusted regexes.

Affected versions

All versions of the regex crate before or equal to 1.5.4 are affected by this issue. The fix is include starting from regex 1.5.5.

Mitigations

We recommend everyone accepting user-controlled regexes to upgrade immediately to the latest version of the regex crate.

Unfortunately there is no fixed set of problematic regexes, as there are practically infinite regexes that could be crafted to exploit this vulnerability. Because of this, we do not recommend denying known problematic regexes.

Acknowledgements

We want to thank Addison Crump for responsibly disclosing this to us according to the Rust security policy, and for helping review the fix.

We also want to thank Andrew Gallant for developing the fix, and Pietro Albini for coordinating the disclosure and writing this advisory.

To clipboard 

{
  "affected": [
    {
      "database_specific": {
        "categories": [
          "denial-of-service"
        ],
        "cvss": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
        "informational": null
      },
      "ecosystem_specific": {
        "affected_functions": null,
        "affects": {
          "arch": [],
          "functions": [],
          "os": []
        }
      },
      "package": {
        "ecosystem": "crates.io",
        "name": "regex",
        "purl": "pkg:cargo/regex"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.0.0-0"
            },
            {
              "fixed": "1.5.5"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "versions": []
    }
  ],
  "aliases": [
    "CVE-2022-24713",
    "GHSA-m5pq-gvj9-9vr8"
  ],
  "database_specific": {
    "license": "CC0-1.0"
  },
  "details": "The Rust Security Response WG was notified that the `regex` crate did not\nproperly limit the complexity of the regular expressions (regex) it parses. An\nattacker could use this security issue to perform a denial of service, by\nsending a specially crafted regex to a service accepting untrusted regexes. No\nknown vulnerability is present when parsing untrusted input with trusted\nregexes.\n\nThis issue has been assigned CVE-2022-24713. The severity of this vulnerability\nis \"high\" when the `regex` crate is used to parse untrusted regexes. Other uses\nof the `regex` crate are not affected by this vulnerability.\n\n## Overview\n\nThe `regex` crate features built-in mitigations to prevent denial of service\nattacks caused by untrusted regexes, or untrusted input matched by trusted\nregexes. Those (tunable) mitigations already provide sane defaults to prevent\nattacks. This guarantee is documented and it\u0027s considered part of the crate\u0027s\nAPI.\n\nUnfortunately a bug was discovered in the mitigations designed to prevent\nuntrusted regexes to take an arbitrary amount of time during parsing, and it\u0027s\npossible to craft regexes that bypass such mitigations. This makes it possible\nto perform denial of service attacks by sending specially crafted regexes to\nservices accepting user-controlled, untrusted regexes.\n\n## Affected versions\n\nAll versions of the `regex` crate before or equal to 1.5.4 are affected by this\nissue. The fix is include starting from  `regex` 1.5.5.\n\n## Mitigations\n\nWe recommend everyone accepting user-controlled regexes to upgrade immediately\nto the latest version of the `regex` crate.\n\nUnfortunately there is no fixed set of problematic regexes, as there are\npractically infinite regexes that could be crafted to exploit this\nvulnerability. Because of this, we do not recommend denying known problematic\nregexes.\n\n## Acknowledgements\n\nWe want to thank Addison Crump for responsibly disclosing this to us according\nto the [Rust security policy][1], and for helping review the fix.\n\nWe also want to thank Andrew Gallant for developing the fix, and Pietro Albini\nfor coordinating the disclosure and writing this advisory.\n\n[1]: https://www.rust-lang.org/policies/security",
  "id": "RUSTSEC-2022-0013",
  "modified": "2023-06-13T13:10:24Z",
  "published": "2022-03-08T12:00:00Z",
  "references": [
    {
      "type": "PACKAGE",
      "url": "https://crates.io/crates/regex"
    },
    {
      "type": "ADVISORY",
      "url": "https://rustsec.org/advisories/RUSTSEC-2022-0013.html"
    },
    {
      "type": "WEB",
      "url": "https://groups.google.com/g/rustlang-security-announcements/c/NcNNL1Jq7Yw"
    }
  ],
  "related": [],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Regexes with large repetitions on empty sub-expressions take a very long time to parse"
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Detection rules are retrieved from Rulezet.