CVE-2025-52556

CRITICALNVD 9.39.3—
EchelonGraph scoreMEDIUM confidence

This critical-severity CVE scores 9.3 under NVD CVSS v3. EPSS exploit probability: 0.2%, top 61% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, nvd
9.3
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 0%CVSS: 9.3Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

rfc3161-client is a Python library implementing the Time-Stamp Protocol (TSP) described in RFC 3161. Prior to version 1.0.3, there is a flaw in the timestamp response signature verification logic. In particular, chain verification is performed 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. This issue has been patched in version 1.0.3. There is no workaround for this issue.

CVSS v3
9.3
EG Score
9.3(medium)
EPSS
4.4%
KEV
Not listed

Published

June 21, 2025

Last Modified

April 15, 2026

References (2)

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
rfc3161-client0.0.2 ... 1.0.2 (9 versions)1.0.3—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 10× in last 7d / 43× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 106 total refreshes for this CVE.

  1. 2026-07-12 05:46 UTCEPSS rescore
  2. 2026-07-11 08:27 UTCEPSS rescore
  3. 2026-07-11 08:27 UTCEPSS rescore
  4. 2026-07-09 19:09 UTCEPSS rescore
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  23. 2026-06-26 04:46 UTCOSV refresh
  24. 2026-06-25 13:49 UTCEPSS rescore
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  1. 2026-06-24 14:04 UTCEPSS rescore
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  25. 2026-06-08 16:05 UTCEG score recompute▲ 9.30
  26. 2026-06-08 14:16 UTCEPSS rescore
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  71. 2026-05-21 12:19 UTCEG score recompute
  72. 2026-05-20 22:37 UTCEPSS rescore
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Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2025-52556?
CVE-2025-52556 is a critical vulnerability published on June 21, 2025. rfc3161-client is a Python library implementing the Time-Stamp Protocol (TSP) described in RFC 3161. Prior to version 1.0.3, there is a flaw in the timestamp response signature verification logic. In particular, chain verification is performed against the TSR's embedded certificates up to the…
When was CVE-2025-52556 disclosed?
CVE-2025-52556 was first published in the National Vulnerability Database on June 21, 2025, with the most recent update on April 15, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2025-52556 actively exploited?
CVE-2025-52556 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 4.4% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2025-52556?
CVE-2025-52556 has a CVSS v3 base score of 9.3 (NVD).
How do I remediate CVE-2025-52556?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2025-52556, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

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