CVE-2025-4516
Use-after-free in "unicode_escape" decoder with error handler
Severity Score
5.9
*CVSS v4
Exploit Likelihood
*EPSS
Affected Versions
*CPE
Public Exploits
0
*Multiple Sources
Exploited in Wild
-
*KEV
Decision
Track
*SSVC
Descriptions
There is an issue in CPython when using `bytes.decode("unicode_escape", error="ignore|replace")`. If you are not using the "unicode_escape" encoding or an error handler your usage is not affected. To work-around this issue you may stop using the error= handler and instead wrap the bytes.decode() call in a try-except catching the DecodeError.
It was discovered that Python incorrectly handled certain unicode characters during decoding. An attacker could possibly use this issue to cause a denial of service. It was discovered that Python incorrectly handled unicode encoding of email headers with list separators in folded lines. An attacker could possibly use this issue to expose sensitive information.
*Credits:
N/A
CVSS Scores
Attack Vector
Attack Complexity
Attack Requirements
Privileges Required
User Interaction
System
Vulnerable | Subsequent
Confidentiality
Integrity
Availability
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality
Integrity
Availability
Attack Vector
Attack Complexity
Authentication
Confidentiality
Integrity
Availability
* Common Vulnerability Scoring System
SSVC
- Decision:Track
Exploitation
Automatable
Tech. Impact
* Organization's Worst-case Scenario
Timeline
- 2025-05-09 CVE Reserved
- 2025-05-15 CVE Published
- 2025-06-03 CVE Updated
- 2025-06-16 EPSS Updated
- ---------- Exploited in Wild
- ---------- KEV Due Date
- ---------- First Exploit
CWE
- CWE-416: Use After Free
CAPEC
References (10)
| URL | Tag | Source |
|---|---|---|
| https://github.com/python/cpython/issues/133767 | Issue Tracking |
| URL | Date | SRC |
|---|
Affected Vendors, Products, and Versions
| Vendor | Product | Version | Other | Status | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Vendor | Product | Version | Other | Status | <-- --> | Vendor | Product | Version | Other | Status |
| Python Software Foundation Search vendor "Python Software Foundation" | CPython Search vendor "Python Software Foundation" for product "CPython" | < 3.9.23 Search vendor "Python Software Foundation" for product "CPython" and version " < 3.9.23" | en |
Affected
| ||||||
| Python Software Foundation Search vendor "Python Software Foundation" | CPython Search vendor "Python Software Foundation" for product "CPython" | >= 3.10.0 < 3.10.18 Search vendor "Python Software Foundation" for product "CPython" and version " >= 3.10.0 < 3.10.18" | en |
Affected
| ||||||
| Python Software Foundation Search vendor "Python Software Foundation" | CPython Search vendor "Python Software Foundation" for product "CPython" | >= 3.11.0 < 3.11.13 Search vendor "Python Software Foundation" for product "CPython" and version " >= 3.11.0 < 3.11.13" | en |
Affected
| ||||||
| Python Software Foundation Search vendor "Python Software Foundation" | CPython Search vendor "Python Software Foundation" for product "CPython" | >= 3.12.0 < 3.12.11 Search vendor "Python Software Foundation" for product "CPython" and version " >= 3.12.0 < 3.12.11" | en |
Affected
| ||||||
| Python Software Foundation Search vendor "Python Software Foundation" | CPython Search vendor "Python Software Foundation" for product "CPython" | >= 3.13.0 < 3.13.4 Search vendor "Python Software Foundation" for product "CPython" and version " >= 3.13.0 < 3.13.4" | en |
Affected
| ||||||