CVE-2025-52556: Rfc3161 client Rfc3161-client Has Insufficient Verification For Vulnerability

CRITICAL
Advisory Identifier: GHSA-6qhv-4h7r-2g9m
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CWE-347
Published
Advisory Summary

CVE-2025-52556 is a CRITICAL rfc3161-client has insufficient verification for vulnerability (CWE-347: Improper Verification of Cryptographic Signature) affecting Rfc3161 client libraries in the PyPI ecosystem. The issue involves rfc3161-client has insufficient verification for timestamp response signatures. Remediation is available by upgrading affected packages to version 1.0.3.

CVE-2025-52556 at a Glance

CVE Identifier CVE-2025-52556
GHSA Identifier GHSA-6qhv-4h7r-2g9m
Severity CRITICAL
CVSS v3.1 Base Score N/A
CWE Classification CWE-347: Improper Verification of Cryptographic Signature
Affected Product Rfc3161 client
Package Ecosystem PyPI
Published Date
Last Updated

How to Fix CVE-2025-52556

To remediate this vulnerability, upgrade all affected Rfc3161 client dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

rfc3161-client fixed: 1.0.3 
pip install rfc3161-client>=1.0.3
Verify Direct and Transitive Dependencies

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

pip show rfc3161-client

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2025-52556, inspect your installed packages using pip:

pip show rfc3161-client

Analyze the terminal output to locate any version of Rfc3161 client in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.0.3), your application is affected.

Note: The pip show rfc3161-client command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-347: Improper Verification of Cryptographic Signature, where the product does not verify, or incorrectly verifies, the cryptographic signature for data. In Rfc3161 client, 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

### Impact `rfc3161-client` 1.0.2 and earlier contain a flaw in their timestamp response signature verification logic. In particular, it performs chain verification against the TSR's embedded certificates up to the trusted root(s), but fails to verify the TSR's own signature against the timestamping leaf certificates. Consequently, vulnerable versions perform insufficient signature validation to properly consider a TSR verified, as the attacker can introduce _any_ TSR signature so long as the embedded leaf chains up to some root TSA. ### Patches Users should immediately upgrade to `rfc3161-client` 1.0.3 or later. ### Workarounds There is no workaround possible. Users should immediately upgrade to a fixed version.

CVE-2025-52556 Affected Rfc3161 client Versions

1 component(s)
Fixed Versions:
1.0.3
Product / Package Ecosystem Affected Versions Fixed Version
rfc3161-client
pypi/rfc3161-client
PyPI
< 1.0.3
1.0.3

References

GitHub Advisory / Wiki ADVISORY
https://github.com/trailofbits/rfc3161-client/security/advisories/GHSA-6qhv-4h7r-2g9m
NVD — CVE-2025-52556 NVD
https://nvd.nist.gov/vuln/detail/CVE-2025-52556
Security Fix Commit FIX COMMIT
https://github.com/trailofbits/rfc3161-client/commit/724a184f953e3f171f85cb223871172b41b0d0dc
Rfc3161 client Source Repository REPOSITORY
https://github.com/trailofbits/rfc3161-client

Frequently Asked Questions

What is CVE-2025-52556?
CVE-2025-52556 is a security vulnerability in Rfc3161 client involving rfc3161-client has insufficient verification for timestamp response signatures under CWE-347: Improper Verification of Cryptographic Signature.
Which Rfc3161 client versions are affected?
Affected versions include releases prior to 1.0.3 across affected packages: rfc3161-client.
What version fixes CVE-2025-52556?
Upgrading to 1.0.3 (or the latest patched release for your respective branch) resolves the vulnerability.
Is rfc3161-client affected?
Yes, rfc3161-client is affected in releases prior to 1.0.3. Upgrade your dependency to 1.0.3 or later.
What CWE is associated with CVE-2025-52556?
CVE-2025-52556 is classified under CWE-347: Improper Verification of Cryptographic Signature (The product does not verify, or incorrectly verifies, the cryptographic signature for data.).
How can I check PyPI dependencies for CVE-2025-52556?
Run the dependency tree command: 'pip show rfc3161-client'. 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-6qhv-4h7r-2g9m",
  "modified" : "2025-06-27T22:02:46Z",
  "published" : "2025-06-20T18:08:40Z",
  "aliases" : [ "CVE-2025-52556" ],
  "summary" : "rfc3161-client has insufficient verification for timestamp response signatures",
  "details" : "### Impact\n\n`rfc3161-client` 1.0.2 and earlier contain a flaw in their timestamp response signature verification logic. In particular, it performs chain verification against the TSR's embedded certificates up to the trusted root(s), but fails to verify the TSR's own signature against the timestamping leaf certificates. Consequently, vulnerable versions perform insufficient signature validation to properly consider a TSR verified, as the attacker can introduce _any_ TSR signature so long as the embedded leaf chains up to some root TSA.\n\n### Patches\n\nUsers should immediately upgrade to `rfc3161-client` 1.0.3 or later.\n\n### Workarounds\n\nThere is no workaround possible. Users should immediately upgrade to a fixed version.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "rfc3161-client"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.0.3"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 1.0.2"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/trailofbits/rfc3161-client/security/advisories/GHSA-6qhv-4h7r-2g9m"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-52556"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/trailofbits/rfc3161-client/commit/724a184f953e3f171f85cb223871172b41b0d0dc"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/trailofbits/rfc3161-client"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-347" ],
    "severity" : "CRITICAL",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-06-20T18:08:40Z",
    "nvd_published_at" : "2025-06-21T02:15:19Z"
  }
}