How severe is CVE-2025-4565?

No CVSS score has been assigned to CVE-2025-4565 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2025-4565?

CVE-2025-4565 affects the following packages: protobuf (PyPI), protobuf (PyPI), protobuf (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2025-4565?

Update protobuf to 4.25.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-4565 is resolved across your whole dependency graph.

How do I detect CVE-2025-4565 in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for protobuf, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2025-4565 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against CVE-2025-4565?

O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-4565 can be triaged on real exposure rather than presence alone.

Is CVE-2025-4565 actively exploited in the wild?

No public exploit code has been indexed for CVE-2025-4565 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2025-4565?

CVE-2025-4565 has an EPSS (Exploit Prediction Scoring System) score of 0.3%, placing it in the 17th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2025-4565?

CVE-2025-4565 is classified as CWE-674 (CWE-674). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2025-4565 published, and has it been updated?

CVE-2025-4565 was published on June 16, 2025 and was last updated on August 12, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

Not in CISA KEV

CVE-2025-4565 — protobuf

Fix: protocolbuffers/protobuf@17838be

CVE-2025-4565 is a CWE-674 vulnerability in protobuf. A fix is available for protobuf — see the affected versions and patch details below.

Unbounded recursion in Python Protobuf

Also known asGHSA-8qvm-5x2c-j2w7PYSEC-2026-1806

Published

Jun 16, 2025

Updated

Aug 12, 2026

Affected

3 pkgs

Patched

3 / 3

Exploits

None indexed

Exploitation data as of Sep 20, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-4565.

EPSS Exploitation Probability

via FIRST.org ↗

0.3%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs17th percentile — riskier than 17% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Real-World Exposure

3 pkgs affected

🐍protobuf🐍protobuf🐍protobuf

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Any project that uses Protobuf Pure-Python backend to parse untrusted Protocol Buffers data containing an arbitrary number of recursive groups, recursive messages or a series of SGROUP tags can be corrupted by exceeding the Python recursion limit. This can result in a Denial of service by crashing the application with a RecursionError. We recommend upgrading to version =>6.31.1 or beyond commit 17838beda2943d08b8a9d4df5b68f5f04f26d901

Affected Packages

3 total 3 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`protobuf`	all versions	4.25.8`pip install --upgrade 'protobuf==4.25.8'`
🐍PyPI	`protobuf`	≥ 5.26.0rc1&&< 5.29.5	5.29.5`pip install --upgrade 'protobuf==5.29.5'`
🐍PyPI	`protobuf`	≥ 6.30.0rc1&&< 6.31.1	6.31.1`pip install --upgrade 'protobuf==6.31.1'`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for protobuf, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update protobuf to 4.25.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-4565 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-4565 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2025-4565. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

The availability impact of this denial-of-service vulnerability is confined to applications that directly integrate the Protobuf package. Within the context of a Red Hat system, the host machine itself is not expected to be impacted, thereby limiting the scope of disruption to individual application instances rather…

Product	Fixed in	Advisory
Red Hat Ansible Automation Platform 2.6 for RHEL 9	`python3.11-protobuf-0:4.25.8-1.el9ap`	RHSA-2026:1249
Red Hat OpenShift Container Platform 4.19	`openshift4/ose-dpu-intel-ipu-vsp-rhel9:v4.19.0-202507081507.p0.gb4d5e23.assembly.stream.el9`	RHSA-2025:10773
Red Hat Ansible Automation Platform 2.6	`ansible-automation-platform-26/gateway-rhel9:1772543959`	RHSA-2026:3960

Ubuntu

USN-7629-1Ubuntu USN-7629-2Ubuntu

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2025-4565 in your dependencies?

O3 Security finds CVE-2025-4565 across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

Scan my dependencies How O3 SCA works