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NVD / CVE Program· CNA GitHub_M

CVE-2022-31117: Double free of buffer during string decoding in ujson

MediumCVSS 5.9 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 24/100)

  • 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: 1.8% (FIRST EPSS); higher than 79.6% of all records.
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
  • Fixed version: py3-ujson (Alpine:v3.16) 5.4.0-r0; ujson (Debian:12) 5.4.0-1; python-ujson (openSUSE:Leap 15.3) 1.35-150100.3.5.1.

Low priority for now. Upgrade to py3-ujson (Alpine:v3.16) 5.4.0-r0; ujson (Debian:12) 5.4.0-1; python-ujson (openSUSE:Leap 15.3) 1.35-150100.3.5.1 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

UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+. In versions prior to 5.4.0 an error occurring while reallocating a buffer for string decoding can cause the buffer to get freed twice. Due to how UltraJSON uses the internal decoder, this double free is impossible to trigger from Python. This issue has been resolved in version 5.4.0 and all users should upgrade to UltraJSON 5.4.0. There are no known workarounds for this issue.

Published
Jul 5, 2022
Updated
Jun 17, 2026
EPSS
1.8% · 79th percentile

Report tools

JSON

Action score

24

Monitor

Low priority for now.

CVSS
23 / 40 · 5.9 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 1.8%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
5.9
CNA · GitHub_M
5.9
agree

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.

Follow CVE-2022-31117

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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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.

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Affected 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.

VendorProduct
ultrajson projectultrajson
fedoraprojectfedora

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • ultrajson ultrajson

    • < 5.4.0affected

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • fedoraproject fedora35
  • fedoraproject fedora36
  • ultrajson project ultrajsonbefore 5.4.0

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Alpine:v3.16py3-ujsonbefore 5.4.0-r05.4.0-r0
Debian:12ujsonbefore 5.4.0-15.4.0-1
openSUSE:Leap 15.3python-ujsonbefore 1.35-150100.3.5.11.35-150100.3.5.1
openSUSE:Tumbleweedpython-ujsonbefore 5.10.0-1.55.10.0-1.5
PyPIujsonbefore 5.4.05.4.0
Red Hat:openstack:16.2::el8python-ujsonbefore 0:2.0.3-3.el8ost0:2.0.3-3.el8ost
Red Hat:openstack:16.2::el8python-ujson-debugsourcebefore 0:2.0.3-3.el8ost0:2.0.3-3.el8ost
Red Hat:openstack:16.2::el8python3-ujsonbefore 0:2.0.3-3.el8ost0:2.0.3-3.el8ost
Red Hat:openstack:16.2::el8python3-ujson-debuginfobefore 0:2.0.3-3.el8ost0:2.0.3-3.el8ost
SUSE:Linux Enterprise Module for Development Tools 15 SP3python-ujsonbefore 1.35-150100.3.5.11.35-150100.3.5.1

Same product

ultrajson project: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-44660UltraJSON: Memory Leak in ujson.dump() on Write Failure
    34Monitor
  • CVE-2022-31116Incorrect handling of invalid surrogate pair characters in ujson
    31Monitor
  • CVE-2026-32875UltraJSON has an integer overflow handling large indent leads to buffer overflow or infinite loop
    30Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2021-45958Dec 31, 2021 · UltraJSON (aka ujson) through 5.1.0 has a stack-based buffer overflow in Buffer_AppendIndentUnchecked (called from encode).
    23Monitor
  • Later →CVE-2026-32874Mar 19, 2026 · UltraJSON has a Memory Leak parsing large integers allows DoS
    30Monitor
  • Later →CVE-2026-54911Jun 22, 2026 · UltraJSON: Malformed/Truncated UTF-8 Accepted and Silently Rewritten in ujson.dumps()
    26Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
alpine:py3-ujson5.4.0-r0 · Alpine:v3.16Package registry (OSV)
debian:ujson5.4.0-1 · Debian:12Package registry (OSV)
opensuse:python-ujson1.35-150100.3.5.1 · openSUSE:Leap 15.3Package registry (OSV)
PyPI:ujson5.4.0Package registry (OSV)
red hat:python-ujson0:2.0.3-3.el8ost · Red Hat:openstack:16.2::el8Package registry (OSV)
red hat:python-ujson-debugsource0:2.0.3-3.el8ost · Red Hat:openstack:16.2::el8Package registry (OSV)
red hat:python3-ujson0:2.0.3-3.el8ost · Red Hat:openstack:16.2::el8Package registry (OSV)
red hat:python3-ujson-debuginfo0:2.0.3-3.el8ost · Red Hat:openstack:16.2::el8Package registry (OSV)
suse:python-ujson1.35-150100.3.5.1 · SUSE:Linux Enterprise Module for Development Tools 15 SP3Package 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.

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Not on record for this CVE: EPSS history · researcher credit · variant or chain candidate · public bounty program.

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.
  • Special conditions such as timing or configuration are required.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-415 · Double Free

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

References

Show all references (3 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records