CVE-2026-18503
Super-linear CPU usage for unbounded input to csv.Sniffer.sniff()
CVE-2026-18503 is fixed in 55 products on 3 platforms, first by Python 3.13 3.13.15, released August 5, 2026. 10 other affected products have no fix yet. It is not reported as exploited. Patch Radar priority: Routine.
RoutineFixed on 3 platforms
CVSS
2.4
Low
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0012
1st percentile
Attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU when applications pass unbounded input to csv.Sniffer.sniff().
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Windows apps | |||
| Python 3.13 | 3.13.15 | Python 3.13 3.13.15 | Aug 5, 2026 |
| Python 3.14 | 3.14.7 | Python 3.14 3.14.7 | Aug 5, 2026 |
| Linux | |||
| pypy3 · Debian 14 | 8.0.1+dfsg-1 | DEBIAN-CVE-2026-18503 | Aug 18, 2026 |
| python · sles 15.7 | 2.7.18-150000.133.1 | SUSE-SU-2026:4411-1 | Oct 1, 2026 |
| python-base · sles 15.7 | 2.7.18-150000.133.1 | SUSE-SU-2026:4411-1 | Oct 1, 2026 |
| python3 · sles 15.6 | 3.6.15-150300.10.129.1 | SUSE-SU-2026:4754-1 | Nov 7, 2026 |
| python3 · sles 15.7 | 3.6.15-150300.10.129.1 | SUSE-SU-2026:4754-1 | Nov 7, 2026 |
| python3-core · sles 15.6 | 3.6.15-150300.10.129.1 | SUSE-SU-2026:4754-1 | Nov 7, 2026 |
| python3-core · sles 15.7 | 3.6.15-150300.10.129.1 | SUSE-SU-2026:4754-1 | Nov 7, 2026 |
| python3.11 · Debian 12.15 (bookworm) | 3.11.2-6+deb12u9 | DEBIAN-CVE-2026-18503 | Aug 18, 2026 |
| python3.11 · amzn 2023 | 3.11.16-1.amzn2023.0.1 | ALAS2023-2026-2125 | Aug 31, 2026 |
| python3.11-debug · amzn 2023 | 3.11.16-1.amzn2023.0.1 | ALAS2023-2026-2125 | Aug 31, 2026 |
| python3.11-debuginfo · amzn 2023 | 3.11.16-1.amzn2023.0.1 | ALAS2023-2026-2125 | Aug 31, 2026 |
| python3.11-debugsource · amzn 2023 | 3.11.16-1.amzn2023.0.1 | ALAS2023-2026-2125 | Aug 31, 2026 |
| python3.11-devel · amzn 2023 | 3.11.16-1.amzn2023.0.1 | ALAS2023-2026-2125 | Aug 31, 2026 |
| python3.11-idle · amzn 2023 | 3.11.16-1.amzn2023.0.1 | ALAS2023-2026-2125 | Aug 31, 2026 |
| python3.11-libs · amzn 2023 | 3.11.16-1.amzn2023.0.1 | ALAS2023-2026-2125 | Aug 31, 2026 |
| python3.11-test · amzn 2023 | 3.11.16-1.amzn2023.0.1 | ALAS2023-2026-2125 | Aug 31, 2026 |
| python3.11-tkinter · amzn 2023 | 3.11.16-1.amzn2023.0.1 | ALAS2023-2026-2125 | Aug 31, 2026 |
| python3.12 · amzn 2023 | 3.12.14-2.amzn2023.0.1 | ALAS2023-2026-2124 | Aug 31, 2026 |
| python3.12-debug · amzn 2023 | 3.12.14-2.amzn2023.0.1 | ALAS2023-2026-2124 | Aug 31, 2026 |
| python3.12-debuginfo · amzn 2023 | 3.12.14-2.amzn2023.0.1 | ALAS2023-2026-2124 | Aug 31, 2026 |
| python3.12-debugsource · amzn 2023 | 3.12.14-2.amzn2023.0.1 | ALAS2023-2026-2124 | Aug 31, 2026 |
| python3.12-devel · amzn 2023 | 3.12.14-2.amzn2023.0.1 | ALAS2023-2026-2124 | Aug 31, 2026 |
| python3.12-idle · amzn 2023 | 3.12.14-2.amzn2023.0.1 | ALAS2023-2026-2124 | Aug 31, 2026 |
| python3.12-libs · amzn 2023 | 3.12.14-2.amzn2023.0.1 | ALAS2023-2026-2124 | Aug 31, 2026 |
| python3.12-test · amzn 2023 | 3.12.14-2.amzn2023.0.1 | ALAS2023-2026-2124 | Aug 31, 2026 |
| python3.12-tkinter · amzn 2023 | 3.12.14-2.amzn2023.0.1 | ALAS2023-2026-2124 | Aug 31, 2026 |
| python3.13 · amzn 2023 | 3.13.15-1.amzn2023.0.1 | ALAS2023-2026-2123 | Aug 31, 2026 |
| python3.13-debug · amzn 2023 | 3.13.15-1.amzn2023.0.1 | ALAS2023-2026-2123 | Aug 31, 2026 |
| python3.13-debuginfo · amzn 2023 | 3.13.15-1.amzn2023.0.1 | ALAS2023-2026-2123 | Aug 31, 2026 |
| python3.13-debugsource · amzn 2023 | 3.13.15-1.amzn2023.0.1 | ALAS2023-2026-2123 | Aug 31, 2026 |
| python3.13-devel · amzn 2023 | 3.13.15-1.amzn2023.0.1 | ALAS2023-2026-2123 | Aug 31, 2026 |
| python3.13-freethreading · amzn 2023 | 3.13.15-1.amzn2023.0.1 | ALAS2023-2026-2123 | Aug 31, 2026 |
| python3.13-freethreading-debug · amzn 2023 | 3.13.15-1.amzn2023.0.1 | ALAS2023-2026-2123 | Aug 31, 2026 |
| python3.13-idle · amzn 2023 | 3.13.15-1.amzn2023.0.1 | ALAS2023-2026-2123 | Aug 31, 2026 |
| python3.13-libs · amzn 2023 | 3.13.15-1.amzn2023.0.1 | ALAS2023-2026-2123 | Aug 31, 2026 |
| python3.13-test · amzn 2023 | 3.13.15-1.amzn2023.0.1 | ALAS2023-2026-2123 | Aug 31, 2026 |
| python3.13-tkinter · amzn 2023 | 3.13.15-1.amzn2023.0.1 | ALAS2023-2026-2123 | Aug 31, 2026 |
| python3.14 · Debian 14 | 3.14.7-1 | DEBIAN-CVE-2026-18503 | Aug 18, 2026 |
| python3.14 · amzn 2023 | 3.14.7-1.amzn2023.0.1 | ALAS2023-2026-2122 | Aug 31, 2026 |
| python3.14-debug · amzn 2023 | 3.14.7-1.amzn2023.0.1 | ALAS2023-2026-2122 | Aug 31, 2026 |
| python3.14-debuginfo · amzn 2023 | 3.14.7-1.amzn2023.0.1 | ALAS2023-2026-2122 | Aug 31, 2026 |
| python3.14-debugsource · amzn 2023 | 3.14.7-1.amzn2023.0.1 | ALAS2023-2026-2122 | Aug 31, 2026 |
| python3.14-devel · amzn 2023 | 3.14.7-1.amzn2023.0.1 | ALAS2023-2026-2122 | Aug 31, 2026 |
| python3.14-freethreading · amzn 2023 | 3.14.7-1.amzn2023.0.1 | ALAS2023-2026-2122 | Aug 31, 2026 |
| python3.14-freethreading-debug · amzn 2023 | 3.14.7-1.amzn2023.0.1 | ALAS2023-2026-2122 | Aug 31, 2026 |
| python3.14-freethreading-devel · amzn 2023 | 3.14.7-1.amzn2023.0.1 | ALAS2023-2026-2122 | Aug 31, 2026 |
| python3.14-freethreading-idle · amzn 2023 | 3.14.7-1.amzn2023.0.1 | ALAS2023-2026-2122 | Aug 31, 2026 |
| python3.14-freethreading-libs · amzn 2023 | 3.14.7-1.amzn2023.0.1 | ALAS2023-2026-2122 | Aug 31, 2026 |
| python3.14-freethreading-test · amzn 2023 | 3.14.7-1.amzn2023.0.1 | ALAS2023-2026-2122 | Aug 31, 2026 |
| python3.14-freethreading-tkinter · amzn 2023 | 3.14.7-1.amzn2023.0.1 | ALAS2023-2026-2122 | Aug 31, 2026 |
| python3.14-idle · amzn 2023 | 3.14.7-1.amzn2023.0.1 | ALAS2023-2026-2122 | Aug 31, 2026 |
| python3.14-libs · amzn 2023 | 3.14.7-1.amzn2023.0.1 | ALAS2023-2026-2122 | Aug 31, 2026 |
| python3.14-test · amzn 2023 | 3.14.7-1.amzn2023.0.1 | ALAS2023-2026-2122 | Aug 31, 2026 |
| python3.14-tkinter · amzn 2023 | 3.14.7-1.amzn2023.0.1 | ALAS2023-2026-2122 | Aug 31, 2026 |
| python3.15 · Debian 14 | 3.15.0~rc1-1 | DEBIAN-CVE-2026-18503 | Aug 18, 2026 |
| python313 · sles 15.7 | 3.13.15-150700.4.56.1 | SUSE-SU-2026:4401-1 | Sep 30, 2026 |
| python313-core · sles 15.7 | 3.13.15-150700.4.56.1 | SUSE-SU-2026:4401-1 | Sep 30, 2026 |
| No fix yet | |||
| Python 2 (Windows apps) | No fix yet | no-fix | n/a |
| Python 3.10 (Windows apps) | No fix yet | no-fix | n/a |
| Python 3.11 (Windows apps) | No fix yet | no-fix | n/a |
| Python 3.12 (Windows apps) | No fix yet | no-fix | n/a |
| Python 3.5 (Windows apps) | No fix yet | no-fix | n/a |
| Python 3.6 (Windows apps) | No fix yet | no-fix | n/a |
| Python 3.7 (Windows apps) | No fix yet | no-fix | n/a |
| Python 3.8 (Windows apps) | No fix yet | no-fix | n/a |
| Python 3.9 (Windows apps) | No fix yet | no-fix | n/a |
| Python3 (macOS) | No fix yet | no-fix | n/a |
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