CVE-2026-54911— UltraJSON: Malformed/Truncated UTF-8 Accepted and Silently Rewritten in ujson.dumps()
Possible ATT&CK Techniques 1AI
T1564.008 · Email Hiding RulesGet alerts for future matching vulnerabilitiesLog in to subscribe
I. Basic Information for CVE-2026-54911
Vulnerability Information
Have questions about the vulnerability? See if Shenlong's analysis helps!
View Shenlong Deep Dive ↗ Although we use advanced large model technology, its output may still contain inaccurate or outdated information.Shenlong tries to ensure data accuracy, but please verify and judge based on the actual situation.
Vulnerability Title
UltraJSON: Malformed/Truncated UTF-8 Accepted and Silently Rewritten in ujson.dumps()
Source: CVE Program / CVE List V5
Vulnerability Description
UltraJSON is a fast JSON encoder and decoder written in pure C with bindings for Python 3.7+. Prior to 5.13.0, ujson.dumps() (or ujson.dump() or ujson.encode()) have a reject_bytes=False option. When set, they may accept malformed or truncated UTF-8 byte sequences, silently rewriting them into different Unicode characters instead of rejecting them. This leads to input validation bypass and data integrity issues. This vulnerability is fixed in 5.13.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Source: CVE Program / CVE List V5
Vulnerability Type
输入验证不恰当
Source: CVE Program / CVE List V5
Vulnerability Title
UltraJSON 输入验证错误漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
ultrajson ultrajson是ultrajson的JSON解码库。 UltraJSON 5.12.1之前版本存在输入验证错误漏洞，该漏洞源于ujson.dumps()的reject_bytes=False选项接受畸形或截断的UTF-8字节序列，导致输入验证绕过和数据完整性问题。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)
Affected Products
II. Public POCs for CVE-2026-54911
| # | POC Description | Source Link | Shenlong Link |
|---|
AI-Generated POCPremium
No public POC found.
Login to generate AI POCIII. Intelligence Information for CVE-2026-54911
请登录查看更多情报信息。
Patches & Fixes for CVE-2026-54911 (1)
Vendor Advisories for CVE-2026-54911 (1)
Other References for CVE-2026-54911 (1)
- 🔗 Release 5.13.0 · ultrajson/ultrajson · GitHubx_refsource_MISC
IV. Related Vulnerabilities
Same product: ultrajson
- CVE-2026-44660
UltraJSON: Memory Leak in ujson.dump() on Write Failure - CVE-2026-32875
UltraJSON has an integer overflow handling large indent lead - CVE-2026-32874
UltraJSON has a Memory Leak parsing large integers allows Do - CVE-2022-31116
Incorrect handling of invalid surrogate pair characters in u - CVE-2022-31117
Double free of buffer during string decoding in ujson
Same vendor: ultrajson
- CVE-2026-44660
UltraJSON: Memory Leak in ujson.dump() on Write Failure - CVE-2026-32875
UltraJSON has an integer overflow handling large indent lead - CVE-2026-32874
UltraJSON has a Memory Leak parsing large integers allows Do - CVE-2022-31116
Incorrect handling of invalid surrogate pair characters in u - CVE-2022-31117
Double free of buffer during string decoding in ujson
Same weakness: CWE-20
- CVE-2026-73658
Trigger.dev: Cross-tenant object store read and write via UR - CVE-2026-49827
WebErpMesv2 has Unauthenticated RCE via Unrestricted File Up - CVE-2026-73418
NextAuth.js: getToken() throws an uncaught exception on malf - CVE-2026-19503
Insufficient OIDC endpoint validation could invoke unintende - CVE-2026-69106
Potential cache poisoning in JFrog Artifactory
V. Comments for CVE-2026-54911
No comments yet