CVE-2024-12254Network attack vector

Service interruption via missing writelines backpressure

Published Dec 6, 2024 · Updated Jul 31, 2026

Resource exhaustion in CPython allows remote attackers to interrupt affected asyncio services through sustained socket writes. The _SelectorSocketTransport.writelines() path batches zero-copy buffers without invoking the protocol's flow-control pause after the write buffer crosses its high-water mark, so queued data grows without bound. Exposure requires CPython 3.12.0 through 3.12.8, 3.13.0 through 3.13.1, or 3.14.0a1 through 3.14.0a2 on Linux or macOS, plus an asyncio protocol that calls writelines().

CVSS severity8.7
High
EPSS probability1.87%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in CPython allows remote attackers to interrupt affected asyncio services through sustained socket writes. The _SelectorSocketTransport.writelines() path batches zero-copy buffers without invoking the protocol's flow-control pause after the write buffer crosses its high-water mark, so queued data grows without bound. Exposure requires CPython 3.12.0 through 3.12.8, 3.13.0 through 3.13.1, or 3.14.0a1 through 3.14.0a2 on Linux or macOS, plus an asyncio protocol that calls writelines().

The record

CVE
CVE-2024-12254
Published
Dec 6, 2024
Updated
Jul 31, 2026
Vendor
Python Software Foundation
Product
CPython
Classifications
CWE-770, CWE-400, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 6, 2024CVE publishedPublication date reported by the CVE source.
  2. Jul 31, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <3.12.9
  2. Affected versionversion=3.12.0 <3.14.0a1
  3. Affected versionversion=3.13.0 <3.13.2
  4. Affected versionversion=3.14.0a1 <3.14.0a3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Python Software Foundation · CPythonversion=0 <3.12.9; version=3.12.0 <3.14.0a1; version=3.13.0 <3.13.2; version=3.14.0a1 <3.14.0a3

Published CVSS scores

8.7Python Software FoundationCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
CWE-400Uncontrolled Resource Consumption
T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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