GHSA-52xf-5p2m-9wrv: S2n tls S2n-tls Has A Potentially Observable Vulnerability

LOW
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CWE-203
Published
Advisory Summary

GHSA-52xf-5p2m-9wrv is a LOW s2n-tls has a potentially observable vulnerability (CWE-203: Observable Discrepancy) affecting S2n tls libraries in the crates.io ecosystem. The issue involves s2n-tls has a potentially observable differences in rsa premaster secret handling. Remediation is available by upgrading affected packages to version 0.2.7.

GHSA-52xf-5p2m-9wrv at a Glance

CVE Identifier N/A
GHSA Identifier GHSA-52xf-5p2m-9wrv
Severity LOW
CVSS v3.1 Base Score N/A
CWE Classification CWE-203: Observable Discrepancy
Affected Product S2n tls
Package Ecosystem crates.io
Published Date
Last Updated

How to Fix GHSA-52xf-5p2m-9wrv

To remediate this vulnerability, upgrade all affected S2n tls dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

s2n-tls fixed: 0.2.7 
Upgrade s2n-tls to 0.2.7
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

inspect dependencies for s2n-tls

How to Check if You Are Affected

To determine whether your application is affected by GHSA-52xf-5p2m-9wrv, inspect your project dependencies for S2n tls:

inspect dependencies for s2n-tls

Analyze the terminal output to locate any version of S2n tls in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 0.2.7), your application is affected.

Note: Verify declared build manifests and deployed runtime container environments.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-203: Observable Discrepancy, where the product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor. In S2n tls, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

When receiving a message from a client that sent an invalid RSA premaster secret, an issue in s2n-tls results in the server performing additional processing when the premaster secret contains an incorrect client hello version. While no practical attack on s2n-tls has been demonstrated, this causes a small timing difference which could theoretically be used as described in the Marvin Attack [1]. We would like to thank Hubert Kario [2] for reporting this issue. ### Impact The extent of this issue is a timing difference. No practical attack on s2n-tls has been demonstrated. This issue affects server applications that permit RSA key exchange. Applications that use the default, built-in blinding feature or properly implement self-service blinding are not affected. Impacted versions: <= v1.4.15. ### Patches The patch is included in v1.4.16 [3]. ### Workarounds Applications can work around this issue by using an s2n-tls security policy that disallows RSA key exchange. If you have any questions or comments about this advisory we ask that you contact AWS/Amazon Security via our vulnerability reporting page [4] or directly via email to [aws-security@amazon.com](mailto:aws-security@amazon.com). Please do not create a public GitHub issue. [1] https://people.redhat.com/~hkario/marvin/ [2] https://github.com/tomato42 [3] https://github.com/aws/s2n-tls/releases/tag/v1.4.16 [4] https://aws.amazon.com/security/vulnerability-reporting

GHSA-52xf-5p2m-9wrv Affected S2n tls Versions

1 component(s)
Fixed Versions:
0.2.7
Product / Package Ecosystem Affected Versions Fixed Version
s2n-tls
 crates.io
< 0.2.7
0.2.7

References

GitHub Advisory / Wiki ADVISORY
https://github.com/aws/s2n-tls/security/advisories/GHSA-52xf-5p2m-9wrv
Security Fix Commit FIX COMMIT
https://github.com/aws/s2n-tls/commit/114ccab0ff2cde491203ac841837d0d39b767412
S2n tls Source Repository REPOSITORY
https://github.com/aws/s2n-tls
S2n tls Release RELEASE
https://github.com/aws/s2n-tls/releases/tag/v1.4.16

Frequently Asked Questions

What is GHSA-52xf-5p2m-9wrv?
GHSA-52xf-5p2m-9wrv is a security vulnerability in S2n tls involving s2n-tls has a potentially observable differences in RSA premaster secret handling under CWE-203: Observable Discrepancy.
Which S2n tls versions are affected?
Affected versions include releases prior to 0.2.7 across affected packages: s2n-tls.
What version fixes GHSA-52xf-5p2m-9wrv?
Upgrading to 0.2.7 (or the latest patched release for your respective branch) resolves the vulnerability.
Is s2n-tls affected?
Yes, s2n-tls is affected in releases prior to 0.2.7. Upgrade your dependency to 0.2.7 or later.
What CWE is associated with GHSA-52xf-5p2m-9wrv?
GHSA-52xf-5p2m-9wrv is classified under CWE-203: Observable Discrepancy (The product behaves differently or sends different responses under different circumstances in a way that is observable to an unauthorized actor.).
How can I check crates.io dependencies for GHSA-52xf-5p2m-9wrv?
Run the dependency tree command: 'inspect dependencies for s2n-tls'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-52xf-5p2m-9wrv",
  "modified" : "2024-06-06T14:26:18Z",
  "published" : "2024-06-06T14:26:18Z",
  "aliases" : [ ],
  "summary" : "s2n-tls has a potentially observable differences in RSA premaster secret handling",
  "details" : "When receiving a message from a client that sent an invalid RSA premaster secret, an issue in s2n-tls results in the server performing additional processing when the premaster secret contains an incorrect client hello version. While no practical attack on s2n-tls has been demonstrated, this causes a small timing difference which could theoretically be used as described in the Marvin Attack [1].\n\nWe would like to thank Hubert Kario [2] for reporting this issue.\n\n\n### Impact\n\nThe extent of this issue is a timing difference. No practical attack on s2n-tls has been demonstrated.\n\nThis issue affects server applications that permit RSA key exchange. Applications that use the default, built-in blinding feature or properly implement self-service blinding are not affected.\n\nImpacted versions: <= v1.4.15.\n\n\n### Patches\n\nThe patch is included in v1.4.16 [3].\n\n### Workarounds\n\nApplications can work around this issue by using an s2n-tls security policy that disallows RSA key exchange.\n\nIf you have any questions or comments about this advisory we ask that you contact AWS/Amazon Security via our vulnerability reporting page [4] or directly via email to [aws-security@amazon.com](mailto:aws-security@amazon.com). Please do not create a public GitHub issue.\n\n[1] https://people.redhat.com/~hkario/marvin/\n[2] https://github.com/tomato42\n[3] https://github.com/aws/s2n-tls/releases/tag/v1.4.16\n[4] https://aws.amazon.com/security/vulnerability-reporting",
  "severity" : [ ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "crates.io",
      "name" : "s2n-tls"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "0.2.7"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 0.2.6"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/aws/s2n-tls/security/advisories/GHSA-52xf-5p2m-9wrv"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/aws/s2n-tls/commit/114ccab0ff2cde491203ac841837d0d39b767412"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/aws/s2n-tls"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/aws/s2n-tls/releases/tag/v1.4.16"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-203" ],
    "severity" : "LOW",
    "github_reviewed" : true,
    "github_reviewed_at" : "2024-06-06T14:26:18Z",
    "nvd_published_at" : null
  }
}