Unbounded recursion in Python Protobuf
Noroxi assessment
Priority: Monitor (action score 32/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.25% (FIRST EPSS).
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
- According to CISA the attack is automatable: targets can be found by mass scanning.
- Fixed version: protocolbuffers Python-Protobuf 4.25.8, 5.29.5, 6.31.1.
Low priority for now. Upgrade to protocolbuffers Python-Protobuf 4.25.8, 5.29.5, 6.31.1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
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
- Published
- Jun 16, 2025
- Updated
- Jun 17, 2026
- EPSS
- 0.2% · 15th percentile
- CWE
- CWE-674
Report tools
Action score
32
Monitor
Low priority for now.
- CVSS
- 32 / 40 · 8.2 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.2%
CISA SSVC decision
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- —
- CNA · Google
- 8.2
- NVD has not scored this yet; the score shown is the CNA’s.
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| protobuf-python | cpe:2.3:a:google:protobuf-python |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- google protobuf-pythonbefore 4.25.8
- google protobuf-python5.26.0 and later · before 5.29.5
- google protobuf-python6.30.0 and later · before 6.31.1
Versions reported by the vendor
Affected version ranges reported by the assigning authority (Google). Independent of NVD's CPE analysis and usually ahead of it.
protocolbuffers Python-Protobuf
- before 4.25.8affected · semver
- before 5.29.5affected · semver
- before 6.31.1affected · semver
- before 4.25.8affected · semver
- before 5.29.5affected · semver
- before 6.31.1affected · semver
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:12 | protobuf | before 3.21.12-3+deb12u1 | 3.21.12-3+deb12u1 |
| Debian:13 | protobuf | before 3.21.12-11+deb13u1 | 3.21.12-11+deb13u1 |
| Debian:14 | protobuf | before 3.21.12-12 | 3.21.12-12 |
| openSUSE:Leap 16.0 | protobuf | before 28.3-160000.3.1 | 28.3-160000.3.1 |
| openSUSE:Leap 16.0 | protobuf-java | before 28.3-160000.3.1 | 28.3-160000.3.1 |
| openSUSE:Leap 16.0 | python-protobuf | before 5.28.3-160000.3.1 | 5.28.3-160000.3.1 |
| openSUSE:Tumbleweed | protobuf | before 31.1-1.1 | 31.1-1.1 |
| PyPI | protobuf | from 5.26.0rc1 · before 5.29.5 | 5.29.5 |
| PyPI | protobuf | from 6.30.0rc1 · before 6.31.1 | 6.31.1 |
| PyPI | protobuf | before 4.25.8 | 4.25.8 |
| Red Hat:ansible_automation_platform_developer:2.6::el9 | python3.11-django | before 0:4.2.27-2.el9ap | 0:4.2.27-2.el9ap |
| Red Hat:ansible_automation_platform_developer:2.6::el9 | python3.11-urllib3 | before 0:2.6.3-1.el9ap | 0:2.6.3-1.el9ap |
| Red Hat:ansible_automation_platform_developer:2.6::el9 | receptor | before 0:1.6.3-2.el9ap | 0:1.6.3-2.el9ap |
| Red Hat:ansible_automation_platform:2.6::el10 | receptor | before 0:1.6.3-2.el10ap | 0:1.6.3-2.el10ap |
| Red Hat:ansible_automation_platform:2.6::el9 | automation-controller-venv-tower | before 0:4.7.8-1.el9ap | 0:4.7.8-1.el9ap |
| Red Hat:ansible_automation_platform:2.6::el9 | python3.11-protobuf | before 0:4.25.8-1.el9ap | 0:4.25.8-1.el9ap |
| Red Hat:ansible_automation_platform:2.6::el9 | python3.11-protobuf-debuginfo | before 0:4.25.8-1.el9ap | 0:4.25.8-1.el9ap |
| Red Hat:ansible_automation_platform:2.6::el9 | python3.11-protobuf-debugsource | before 0:4.25.8-1.el9ap | 0:4.25.8-1.el9ap |
| SUSE:Linux Enterprise Micro 5.3 | protobuf | before 3.9.2-150200.4.27.1 | 3.9.2-150200.4.27.1 |
| SUSE:Linux Enterprise Micro 5.3 | protobuf | before 25.1-150400.9.16.1 | 25.1-150400.9.16.1 |
| SUSE:Linux Enterprise Micro 5.5 | protobuf | before 25.1-150500.12.11.1 | 25.1-150500.12.11.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | protobuf | before 25.1-150600.16.13.1 | 25.1-150600.16.13.1 |
| SUSE:Linux Enterprise Module for Basesystem 15 SP6 | protobuf | before 25.1-150600.16.13.1 | 25.1-150600.16.13.1 |
| SUSE:Linux Enterprise Server 16.0 | protobuf-java | before 28.3-160000.3.1 | 28.3-160000.3.1 |
+4
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| protocolbuffers Python-Protobuf | 4.25.8 | Vendor (CNA) |
| protocolbuffers Python-Protobuf | 5.29.5 | Vendor (CNA) |
| protocolbuffers Python-Protobuf | 6.31.1 | Vendor (CNA) |
| debian:protobuf | 3.21.12-3+deb12u1 · Debian:12 | Package registry (OSV) |
| opensuse:protobuf | 25.1-150600.16.13.1 · openSUSE:Leap 15.6 | Package registry (OSV) |
| opensuse:protobuf-java | 28.3-160000.3.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| opensuse:python-protobuf | 5.28.3-160000.3.1 · openSUSE:Leap 16.0 | Package registry (OSV) |
| PyPI:protobuf | 4.25.8 | Package registry (OSV) |
| PyPI:protobuf | 5.29.5 | Package registry (OSV) |
| PyPI:protobuf | 6.31.1 | Package registry (OSV) |
| red hat:automation-controller-venv-tower | 0:4.7.8-1.el9ap · Red Hat:ansible_automation_platform:2.6::el9 | Package registry (OSV) |
| red hat:python3.11-django | 0:4.2.27-2.el9ap · Red Hat:ansible_automation_platform_developer:2.6::el9 | Package registry (OSV) |
| red hat:python3.11-protobuf | 0:4.25.8-1.el9ap · Red Hat:ansible_automation_platform:2.6::el9 | Package registry (OSV) |
| red hat:python3.11-protobuf-debuginfo | 0:4.25.8-1.el9ap · Red Hat:ansible_automation_platform:2.6::el9 | Package registry (OSV) |
| red hat:python3.11-protobuf-debugsource | 0:4.25.8-1.el9ap · Red Hat:ansible_automation_platform:2.6::el9 | Package registry (OSV) |
| red hat:python3.11-urllib3 | 0:2.6.3-1.el9ap · Red Hat:ansible_automation_platform_developer:2.6::el9 | Package registry (OSV) |
| red hat:receptor | 0:1.6.3-2.el10ap · Red Hat:ansible_automation_platform:2.6::el10 | Package registry (OSV) |
| suse:protobuf | 25.1-150400.9.16.1 · SUSE:Linux Enterprise Micro 5.3 | Package registry (OSV) |
| suse:protobuf | 25.1-150600.16.13.1 · SUSE:Linux Enterprise Module for Basesystem 15 SP6 | Package registry (OSV) |
| suse:protobuf-java | 28.3-160000.3.1 · SUSE:Linux Enterprise Server 16.0 | Package registry (OSV) |
| suse:python-protobuf | 5.28.3-160000.3.1 · SUSE:Linux Enterprise Server 16.0 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
- Alexis Challande - TrailBits Ecosystem Security Teamfinder
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- Integrity
- Availability
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- X
Weakness class (CWE)
CWE-674 · Uncontrolled RecursionCVSS vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/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
nvd-secondary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Change log
- Fix✗ → ✓
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References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.