CVE-2025-52556

9.3 CRITICAL 0.2% exploit odds Fix listed Crypto Library

What it is

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.

At a glance

Exploitability: Can be exploited over the network without logging in. High risk of data exposure, data tampering.
Exploit odds: 0.2% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2025-06-21 02:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-06-17 09:36 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.2% in the next 30 days (EPSS).
Severity: 9.3 CRITICAL (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2025-06-21 02:15 UTC
Last modified: 2026-06-17 09:36 UTC
Exploit probability: 0.2% · EPSS, next 30 days
Weakness: CWE-347
Record status: Deferred

Attack profile CVSS 4.0 · 9.3

Attack vector: Network
Complexity: Low
Attack requirements: None
Privileges needed: None
User interaction: None
Confidentiality: High
Integrity: High
Availability: None

Raw vector

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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2025-52556.md and follow it. Check whether this project is affected by CVE-2025-52556. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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Fix and advisories

References

NVD record · CVE.org record