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CVE-2021-45958

22
FAUCET Score

CVE-2021-45958 is a stack-based buffer overflow vulnerability in UltraJSON (ujson) versions through 5.1.0, affecting various Debian and Fedora distributions. This medium-severity flaw (CVSS 5.5) can be triggered by a local attacker through user interaction, potentially leading to a denial of service due to a large amount of indentation during JSON encoding. There is currently no evidence of active exploitation, public exploit code, or significant community discussion surrounding this vulnerability.

Impacted Technologies

VendorProductVersion(s)CPE
< 5.2.0CPE matchmatch criteria
cpe:2.3:a:ultrajson_project:ultrajson:*:*:*:*:*:python:*:*
9.0CPE matchmatch criteria
cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*
35CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*
36CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:36:*:*:*:*:*:*:*
37CPE matchmatch criteria
cpe:2.3:o:fedoraproject:fedora:37:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

5.5MEDIUM

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

Attack Vector
LOCAL
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
REQUIRED
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
1.8
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.55%
Probability of exploitation in next 30 days
EPSS Percentile
72.5%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0155 is in the 83rd percentile among its peer group of 5,765 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.0 Bluesky, 0.0 Mastodon, and 0.1 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (2)

github_advisorypatch availablevia nvd_reference
View patch
pippatch availablevia ghsa
Product: ujsonFixed in: 5.2.0

Vendor Advisories (1)

pipGHSA-fh56-85cw-5pq6medium

UltraJSON vulnerable to Out-of-bounds Write

Jan 21, 2022

References

bugs.chromium.org / p/oss-fuzz/issues/detail
ExploitIssue TrackingThird Party Advisory
github.com / google/oss-fuzz-vulns/blob/main/vulns/ujson/OSV-2021-955.yaml
ExploitThird Party Advisory
github.com / ultrajson/ultrajson/issues/501
ExploitIssue TrackingThird Party Advisory
github.com / ultrajson/ultrajson/issues/502
Issue TrackingPatchThird Party Advisory
github.com / ultrajson/ultrajson/pull/504
PatchThird Party Advisory
lists.debian.org / debian-lts-announce/2022/02/msg00023.html
Mailing ListThird Party Advisory
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/CN7W3GOXALINKFUUE7ICQIC2EF5HNKUQ
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/NAU5N4A7EUK2AMUCOLYDD5ARXAJYZBD2
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/O6JUWQTJLA2CMG4CJN7DCUVSOXLZIIXL
lists.fedoraproject.org / archives/list/package-announce%40lists.fedoraproject.org/message/ULX35TSWLBBIMEH44MUORPXYYRZKEDC6