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Vulnerability Intelligence Report
Unbounded memory buffering in SelectorSocketTransport.writelines()

CVE-2024-12254

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.

No Active Exploit Signals
CVSS Base Score
8.7
HIGH
EPSS Probability:1.88%
Executive Threat Verdict
Evaluating...
Evaluating Threat Landscape...
Assessing known weaponization, exploitation telemetry, and federal advisories.
Attack Surface
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Authentication
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Weaponization
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SSVC Action
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Weaknesses (CWE)

CWE-400 ↗CWE-400 Uncontrolled Resource Consumption
CWE-770 ↗CWE-770 Allocation of Resources Without Limits or Throttling

Affected Products & Versions

Vendor Product Affected Versions
Python Software Foundation CPython 0 < 3.12.9 (affected), 3.13.0 < 3.13.2 (affected), 3.14.0a1 < 3.14.0a3 (affected)

References & Technical Advisories

No reference links found.

Threat Intelligence Signals

EPSS Score
1.880%

Identity & Timeline

StatusPUBLISHED
Assigning AuthorityPython Software Foundation · Vendor · USA
Reserved2024-12-05T16:17:55
Published2024-12-06T15:19:41
Last Updated2026-07-31T14:08:25

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