How severe is CVE-2026-0994?

No CVSS score has been assigned to CVE-2026-0994 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-0994?

CVE-2026-0994 affects the following packages: protobuf (PyPI), protobuf (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2026-0994?

Update protobuf to 6.33.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-0994 is resolved across your whole dependency graph.

How do I detect CVE-2026-0994 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-2026-0994 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2026-0994 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-0994 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-2026-0994?

CVE-2026-0994 has an EPSS (Exploit Prediction Scoring System) score of 0.7%, placing it in the 54th 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-2026-0994?

CVE-2026-0994 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-2026-0994 published, and has it been updated?

CVE-2026-0994 was published on January 23, 2026 and was last updated on October 28, 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-2026-0994 — protobuf

Fix: protocolbuffers/protobuf#25239

CVE-2026-0994 is a CWE-674 vulnerability in protobuf. A fix is available for protobuf — see the affected versions and patch details below.

Denial of Service in Python Protobuf

Also known asGHSA-7gcm-g887-7qv7PYSEC-2026-1805

Published

Jan 23, 2026

Updated

Oct 28, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Nov 3, 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-2026-0994.

EPSS Exploitation Probability

via FIRST.org ↗

0.7%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs54th percentile — riskier than 54% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

2 pkgs affected

🐍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

Due to missing recursion depth accounting inside the internal Any-handling logic, an attacker can supply deeply nested Any structures that bypass the intended recursion limit, eventually exhausting Python’s recursion stack and causing a RecursionError.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`protobuf`	≥ 6.30.0rc1&&< 6.33.5	6.33.5`pip install --upgrade 'protobuf==6.33.5'`
🐍PyPI	`protobuf`	all versions	5.29.6`pip install --upgrade 'protobuf==5.29.6'`

Affected Products

1 product · 1 configurations

Application

protobufgoogle

≤ 33.4

range

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 6.33.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-0994 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

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 HatImportant

This vulnerability is rated Important for Red Hat products. The flaw in `protobuf` allows a remote attacker to trigger a denial-of-service by providing specially crafted, deeply nested `google.protobuf.Any` messages to the `google.protobuf.json_format.ParseDict()` function. This bypasses the intended recursion depth…

Workaround published by Red Hat

Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.

Source: Red Hat security advisory for CVE-2026-0994 (CC BY 4.0)

Product	Fixed in	Advisory
Red Hat Ansible Automation Platform 2.5 for RHEL 8	`python3.12-protobuf-0:5.29.6-1.el8ap`	RHSA-2026:3959
Red Hat Ansible Automation Platform 2.6 for RHEL 9	`python3.12-protobuf-0:5.29.6-1.el9ap`	RHSA-2026:3958
Red Hat Enterprise Linux 10	`protobuf-0:3.19.6-15.el10_1`	RHSA-2026:3094
Red Hat Enterprise Linux 10.0 Extended Update Support	`protobuf-0:3.19.6-11.el10_0.1`	RHSA-2026:3218
Red Hat Enterprise Linux 9	`protobuf-0:3.14.0-17.el9_7`	RHSA-2026:3095
Red Hat Enterprise Linux 9.0 Update Services for SAP Solutions	`protobuf-0:3.14.0-9.el9_0.1`	RHSA-2026:3097
Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions	`protobuf-0:3.14.0-13.el9_2.1`	RHSA-2026:3220
Red Hat Enterprise Linux 9.4 Extended Update Support	`protobuf-0:3.14.0-13.el9_4.1`	RHSA-2026:3059

Frequently Asked Questions

A denial-of-service (DoS) vulnerability exists in google.protobuf.json_format.ParseDict() in Python, where the max_recursion_depth limit can be bypassed when parsing nested google.protobuf.Any messages. Due to missing recursion depth accounting inside the internal Any-handling logic, an attacker can supply deeply nested Any structures that bypass the intended recursion limit, eventually exhausting Python’s recursion stack and causing a RecursionError.

O3 Security · Impact-Aware SCA

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