What is the CVSS score of CVE-2026-31048?

CVE-2026-31048 has a CVSS 3.1 base score of 9.8 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H. EPSS exploitation probability: 0.0%.

Which versions of Pyro3 are affected by CVE-2026-31048?

Pyro 3.x deployments are vulnerable to remote code execution attacks delivered through the network, potentially compromising all instances exposed to network connections.

How to fix or mitigate CVE-2026-31048?

Within 24 hours, identify all Pyro 3.x deployments in the environment and document their current network exposure, access controls, and business criticality. Within 7 days, implement firewall rules and network segmentation to restrict Pyro daemon access to trusted internal clients only; disable external connectivity if operationally feasible. Within 30 days, develop and execute a migration plan from Pyro 3.x to Pyro 4.x or alternative RPC frameworks, as no patch for the 3.x line is expected from the vendor.

Pyro3 CVE-2026-31048

EUVD-2026-22059 CRITICAL

Code Injection (CWE-94)

2026-04-13 mitre

RCE Code Injection N A

9.8

CVSS 3.1 · NVD

Severity by source

NVD PRIMARY

9.8 CRITICAL

AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

vuln.today AI

9.8 CRITICAL

Pyro3 unpickles untrusted client messages by default over the network with no authentication or interaction, yielding full code execution, so AV:N/AC:L/PR:N/UI:N and C/I/A all High.

3.1 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

4.0 AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Primary rating from NVD.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Jul 24, 2026 - 08:08 vuln.today

CVSS changed

Apr 15, 2026 - 16:22 NVD

9.8 (CRITICAL)

EUVD ID Assigned

Apr 13, 2026 - 19:30 euvd

EUVD-2026-22059

CVE Published

Apr 13, 2026 - 00:00 nvd

CRITICAL 9.8

DescriptionCVE.org

An issue in the <code>pickle</code> protocol of Pyro v3.x allows attackers to execute arbitrary code via supplying a crafted pickled string message.

AnalysisAI

Remote code execution in Pyro (Python Remote Objects) 3.x arises because the wire protocol deserializes untrusted client messages with Python's pickle module, letting an attacker who can reach a Pyro daemon run arbitrary code by sending a crafted pickled message. All Pyro 3.x deployments that accept network connections are affected, and CWE-94 code injection combined with the CVSS 9.8 rating reflects full compromise of the host process. There is no public exploit identified at time of analysis, and the low EPSS score (0.02%) suggests no observed opportunistic exploitation despite the trivial technical requirements.

Technical ContextAI

Pyro3 is a legacy Python RPC framework that serializes remote method calls and their arguments for transport between clients and a Pyro daemon. The flaw is the classic insecure-deserialization pattern (CWE-94 / code injection): the protocol layer (referenced at Pyro/protocol.py lines 672-711) unpickles incoming byte streams, and pickle's __reduce__ mechanism executes arbitrary callables during object reconstruction. Because pickle is not a safe serialization format for untrusted input, any endpoint that unpickles attacker-controlled bytes effectively grants code execution; the CPE data is unhelpful here (listed as 'n/a'), so affected-product identity comes from the reference URLs pointing to the irmen/Pyro3 repository rather than structured CPE.

RemediationAI

No vendor-released patched version is identified at time of analysis, and Pyro3 is a retired codebase; the strongest remediation is to migrate off Pyro3 to a maintained RPC framework or a Pyro version/serializer that does not unpickle untrusted data, since pickle-based transport is insecure by design. As compensating controls: restrict network access to the Pyro daemon port so only trusted, authenticated hosts can connect (e.g., firewall the Pyro port to a management subnet or bind it to localhost), which prevents untrusted clients from delivering pickled payloads but breaks legitimate remote clients that rely on open access; require transport-level mutual authentication/VPN in front of the daemon so unauthenticated peers cannot reach the deserializer; and consult Pyro's own security guidance (github.com/irmen/Pyro3/blob/master/docs/9-security.html#L341-L346) and the advisory GHSA-7625-w9h5-83rv for configuration hardening. Treat any deployment that accepts pickle from clients as trust-equivalent to granting those clients shell access.