CVE-2024-12254
Unbounded memory buffering in SelectorSocketTransport.writelines()
Severity Score
Exploit Likelihood
Affected Versions
Public Exploits
0Exploited in Wild
-Decision
Descriptions
Starting in Python 3.12.0, the asyncio._SelectorSocketTransport.writelines() method would not "pause" writing and signal to the Protocol to drain the buffer to the wire once the write buffer reached the "high-water mark". Because of this, Protocols would not periodically drain the write buffer potentially leading to memory exhaustion. This vulnerability likely impacts a small number of users, you must be using Python 3.12.0 or later, on macOS or Linux, using the asyncio module with protocols, and using .writelines() method which had new zero-copy-on-write behavior in Python 3.12.0 and later. If not all of these factors are true then your usage of Python is unaffected.
A flaw was found in Python. In certain configurations, the `asyncio._SelectorSocketTransport.writelines()` method fails to signal the protocol to clear the write buffer when it approaches capacity. Because of this, protocols would not periodically drain the write buffer, potentially leading to a denial of service via memory exhaustion.
This update for python312 fixes the following issues. Functions 'urllib.parse.urlsplit' and 'urlparse' accept domain names including square brackets. Unbounded memory buffering in SelectorSocketTransport.writelines. Other bug fixes.
CVSS Scores
SSVC
- Decision:Attend
Timeline
- 2024-12-05 CVE Reserved
- 2024-12-06 CVE Published
- 2025-04-04 CVE Updated
- 2025-07-02 EPSS Updated
- ---------- Exploited in Wild
- ---------- KEV Due Date
- ---------- First Exploit
CWE
- CWE-400: Uncontrolled Resource Consumption
- CWE-770: Allocation of Resources Without Limits or Throttling
CAPEC
References (8)
URL | Tag | Source |
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https://github.com/python/cpython/issues/127655 | Issue Tracking |
URL | Date | SRC |
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Affected Vendors, Products, and Versions
Vendor | Product | Version | Other | Status | ||||||
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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" | >= 3.12.0 < 3.12.9 Search vendor "Python Software Foundation" for product "CPython" and version " >= 3.12.0 < 3.12.9" | en |
Affected
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Python Software Foundation Search vendor "Python Software Foundation" | CPython Search vendor "Python Software Foundation" for product "CPython" | >= 3.13.0 < 3.13.2 Search vendor "Python Software Foundation" for product "CPython" and version " >= 3.13.0 < 3.13.2" | en |
Affected
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