GHSA-7gcm-g887-7qv7 CVE-2026-0994 PYSEC-2026-1805

protobuf affected by a JSON recursion depth bypass

High PyPI

Severity: 8.2 / 10; High · CVSS 4.0
Exploit chance (EPSS): 0.71%; Chance of exploitation in the next 30 days. Higher than 53.61% of scored vulnerabilities.
Known exploited: No; Not in CISA's catalog
Weakness: CWE-674 Uncontrolled Recursion
Fix: 5.29.6; Upgrade protobuf to this version or later

Description

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.

Affected versions

PyPI

Package	Vulnerable	Fixed in
protobuf	`>= 6.30.0rc1, <= 6.33.4`	No fix yet
protobuf	`< 5.29.6`	`5.29.6`
protobuf	`>= 6.30.0rc1, < 6.33.5`	`6.33.5`
protobuf	`< 5.29.6`	`5.29.6`
protobuf	`< 5.29.6` `>= 6.30.0rc1, < 6.33.5`	`5.29.6` `6.33.5`

How to fix

Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.

protobuf PyPI → `5.29.6`

pip

pip install --upgrade "protobuf>=5.29.6"

poetry

poetry add "protobuf>=5.29.6"

uv

uv add "protobuf>=5.29.6"

Severity breakdown

CVSS 4.0 8.2

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

Attack vector: Network
Attack complexity: Low
Attack requirements: Present
Privileges required: None
User interaction: None
Confidentiality (vulnerable system): None
Integrity (vulnerable system): None
Availability (vulnerable system): High
Confidentiality (subsequent systems): None
Integrity (subsequent systems): None
Availability (subsequent systems): Low

CVSS 3.1 7.5

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

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Weakness

CWE-674: Uncontrolled Recursion

The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.

How to prevent it

Implementation: Ensure that an end condition will be reached under all logic conditions. The end condition may include checking against the depth of recursion and exiting with an error if the recursion goes too deep. The complexity of the end condition contributes to the effectiveness of this action.
Implementation: Increase the stack size.

References

Advisories

Fixes and patches

Packages

Timeline

Jan 23, 2026 Published
Sep 10, 2026 Last updated by the source
Oct 31, 2026 Latest EPSS score

Advisory	Severity	Why it's related
GHSA-8qvm-5x2c-j2w7 protobuf-python has a potential Denial of Service issue	High	Also affects protobuf
GHSA-8gq9-2x98-w8hf protobuf-cpp and protobuf-python have potential Denial of Service issue	High	Also affects protobuf
PYSEC-2022-48 Withdrawn Advisory: NULL Pointer Dereference in Protocol Buffers	High	Also affects protobuf
GHSA-jwvw-v7c5-m82h protobuf susceptible to buffer overflow	High	Also affects protobuf
GHSA-hqq3-7jhf-c5jx Forge: Denial of service in TLS record processing via call stack exhaustion	High	Same weakness, CWE-674
GHSA-wwpr-jff3-395c Crass: A large number of adjacent CSS comments can trigger a SystemStackError	Medium	Same weakness, CWE-674
GHSA-6jxj-px6v-747w Crass: Deeply nested CSS blocks and functions can trigger a SystemStackError or excessive memory usage	Medium	Same weakness, CWE-674
GHSA-vvm8-gf78-28g4 Go JOSE: Panics in JSON parsing	Medium	Same weakness, CWE-674

Credits: hwong557, lucas42, micahcassel, mula2812

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