CVE-2024-12254: Python Software Foundation CPython · Uncontrolled Resource Consumption
Affects Python Software Foundation CPythonSource CVE Database V5
Not known to be exploited · CVSS 8.7 High : upgrade to 3.13.2 or 3.12.9 soon.
Data as of 29 Oct 2026, 19:04 UTC
- EPSS
- 1.8% chance of exploitation in 30 days – higher than 79% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 3.13.2, 3.12.9
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 6 Dec 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.
What to do
Upgrade Python Software Foundation CPython to 3.13.2 or 3.12.9.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
GitHubCPythonpkg:github/CPythonOther threats | Affected
| Fixed in
|
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
If you cannot patch yet, users should avoid using the asyncio._SelectorSocketTransport.writelines() method in Python 3.12.0 and later on macOS or Linux with protocols, or implement application-level controls to manage write buffer usage.
Description
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.
References
- github.com/python/cpython/issues/127655 (opens in a new tab)
- github.com/python/cpython/pull/127656 (opens in a new tab)
- mail.python.org/archives/list/security-announce@python.org/thread/H4O3UBAOAQQXGT4RE3E4XQYR5XLROORB/ (opens in a new tab)
- github.com/python/cpython/commit/71e8429ac8e2adc10084ab5ec29a62f4b6671a82 (opens in a new tab)
- github.com/python/cpython/commit/9aa0deb2eef2655a1029ba228527b152353135b5 (opens in a new tab)
- github.com/python/cpython/commit/e991ac8f2037d78140e417cc9a9486223eb3e786 (opens in a new tab)
- openwall.com/lists/oss-security/2024/12/06/1 (opens in a new tab)
- security.netapp.com/advisory/ntap-20250404-0010/ (opens in a new tab)