# 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. - Web page: https://patchblox.com/security/cve/CVE-2026-18503 - Priority: Routine - CVSS: 2.4 (Low) - EPSS: 0.0012 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Aug 10, 2026 - Weakness: Inefficient CPU Computation - Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-18503 ## Description 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 | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Windows apps | Python 3.13 | 3.13.15 | [Python 3.13 3.13.15](https://patchblox.com/security/data/fix/windows-app/python.python.3.13-3.13.15.md) | Aug 5, 2026 | | Windows apps | Python 3.14 | 3.14.7 | [Python 3.14 3.14.7](https://patchblox.com/security/data/fix/windows-app/python.python.3.14-3.14.7.md) | Aug 5, 2026 | | Linux | pypy3 Debian 14 | 8.0.1+dfsg-1 | [DEBIAN-CVE-2026-18503](https://patchblox.com/security/data/fix/linux/debian-cve-2026-18503.md) | Aug 18, 2026 | | Linux | python sles 15.7 | 2.7.18-150000.133.1 | [SUSE-SU-2026:4411-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4411-1.md) | Oct 1, 2026 | | Linux | python-base sles 15.7 | 2.7.18-150000.133.1 | [SUSE-SU-2026:4411-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4411-1.md) | Oct 1, 2026 | | Linux | python3 sles 15.6 | 3.6.15-150300.10.129.1 | [SUSE-SU-2026:4754-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4754-1.md) | Nov 7, 2026 | | Linux | python3 sles 15.7 | 3.6.15-150300.10.129.1 | [SUSE-SU-2026:4754-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4754-1.md) | Nov 7, 2026 | | Linux | python3-core sles 15.6 | 3.6.15-150300.10.129.1 | [SUSE-SU-2026:4754-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4754-1.md) | Nov 7, 2026 | | Linux | python3-core sles 15.7 | 3.6.15-150300.10.129.1 | [SUSE-SU-2026:4754-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4754-1.md) | Nov 7, 2026 | | Linux | python3.11 Debian 12.15 (bookworm) | 3.11.2-6+deb12u9 | [DEBIAN-CVE-2026-18503](https://patchblox.com/security/data/fix/linux/debian-cve-2026-18503.md) | Aug 18, 2026 | | Linux | python3.11 amzn 2023 | 3.11.16-1.amzn2023.0.1 | [ALAS2023-2026-2125](https://patchblox.com/security/data/fix/linux/alas2023-2026-2125.md) | Aug 31, 2026 | | Linux | python3.11-debug amzn 2023 | 3.11.16-1.amzn2023.0.1 | [ALAS2023-2026-2125](https://patchblox.com/security/data/fix/linux/alas2023-2026-2125.md) | Aug 31, 2026 | | Linux | python3.11-debuginfo amzn 2023 | 3.11.16-1.amzn2023.0.1 | [ALAS2023-2026-2125](https://patchblox.com/security/data/fix/linux/alas2023-2026-2125.md) | Aug 31, 2026 | | Linux | python3.11-debugsource amzn 2023 | 3.11.16-1.amzn2023.0.1 | [ALAS2023-2026-2125](https://patchblox.com/security/data/fix/linux/alas2023-2026-2125.md) | Aug 31, 2026 | | Linux | python3.11-devel amzn 2023 | 3.11.16-1.amzn2023.0.1 | [ALAS2023-2026-2125](https://patchblox.com/security/data/fix/linux/alas2023-2026-2125.md) | Aug 31, 2026 | | Linux | python3.11-idle amzn 2023 | 3.11.16-1.amzn2023.0.1 | [ALAS2023-2026-2125](https://patchblox.com/security/data/fix/linux/alas2023-2026-2125.md) | Aug 31, 2026 | | Linux | python3.11-libs amzn 2023 | 3.11.16-1.amzn2023.0.1 | [ALAS2023-2026-2125](https://patchblox.com/security/data/fix/linux/alas2023-2026-2125.md) | Aug 31, 2026 | | Linux | python3.11-test amzn 2023 | 3.11.16-1.amzn2023.0.1 | [ALAS2023-2026-2125](https://patchblox.com/security/data/fix/linux/alas2023-2026-2125.md) | Aug 31, 2026 | | Linux | python3.11-tkinter amzn 2023 | 3.11.16-1.amzn2023.0.1 | [ALAS2023-2026-2125](https://patchblox.com/security/data/fix/linux/alas2023-2026-2125.md) | Aug 31, 2026 | | Linux | python3.12 amzn 2023 | 3.12.14-2.amzn2023.0.1 | [ALAS2023-2026-2124](https://patchblox.com/security/data/fix/linux/alas2023-2026-2124.md) | Aug 31, 2026 | | Linux | python3.12-debug amzn 2023 | 3.12.14-2.amzn2023.0.1 | [ALAS2023-2026-2124](https://patchblox.com/security/data/fix/linux/alas2023-2026-2124.md) | Aug 31, 2026 | | Linux | python3.12-debuginfo amzn 2023 | 3.12.14-2.amzn2023.0.1 | [ALAS2023-2026-2124](https://patchblox.com/security/data/fix/linux/alas2023-2026-2124.md) | Aug 31, 2026 | | Linux | python3.12-debugsource amzn 2023 | 3.12.14-2.amzn2023.0.1 | [ALAS2023-2026-2124](https://patchblox.com/security/data/fix/linux/alas2023-2026-2124.md) | Aug 31, 2026 | | Linux | python3.12-devel amzn 2023 | 3.12.14-2.amzn2023.0.1 | [ALAS2023-2026-2124](https://patchblox.com/security/data/fix/linux/alas2023-2026-2124.md) | Aug 31, 2026 | | Linux | python3.12-idle amzn 2023 | 3.12.14-2.amzn2023.0.1 | [ALAS2023-2026-2124](https://patchblox.com/security/data/fix/linux/alas2023-2026-2124.md) | Aug 31, 2026 | | Linux | python3.12-libs amzn 2023 | 3.12.14-2.amzn2023.0.1 | [ALAS2023-2026-2124](https://patchblox.com/security/data/fix/linux/alas2023-2026-2124.md) | Aug 31, 2026 | | Linux | python3.12-test amzn 2023 | 3.12.14-2.amzn2023.0.1 | [ALAS2023-2026-2124](https://patchblox.com/security/data/fix/linux/alas2023-2026-2124.md) | Aug 31, 2026 | | Linux | python3.12-tkinter amzn 2023 | 3.12.14-2.amzn2023.0.1 | [ALAS2023-2026-2124](https://patchblox.com/security/data/fix/linux/alas2023-2026-2124.md) | Aug 31, 2026 | | Linux | python3.13 amzn 2023 | 3.13.15-1.amzn2023.0.1 | [ALAS2023-2026-2123](https://patchblox.com/security/data/fix/linux/alas2023-2026-2123.md) | Aug 31, 2026 | | Linux | python3.13-debug amzn 2023 | 3.13.15-1.amzn2023.0.1 | [ALAS2023-2026-2123](https://patchblox.com/security/data/fix/linux/alas2023-2026-2123.md) | Aug 31, 2026 | | Linux | python3.13-debuginfo amzn 2023 | 3.13.15-1.amzn2023.0.1 | [ALAS2023-2026-2123](https://patchblox.com/security/data/fix/linux/alas2023-2026-2123.md) | Aug 31, 2026 | | Linux | python3.13-debugsource amzn 2023 | 3.13.15-1.amzn2023.0.1 | [ALAS2023-2026-2123](https://patchblox.com/security/data/fix/linux/alas2023-2026-2123.md) | Aug 31, 2026 | | Linux | python3.13-devel amzn 2023 | 3.13.15-1.amzn2023.0.1 | [ALAS2023-2026-2123](https://patchblox.com/security/data/fix/linux/alas2023-2026-2123.md) | Aug 31, 2026 | | Linux | python3.13-freethreading amzn 2023 | 3.13.15-1.amzn2023.0.1 | [ALAS2023-2026-2123](https://patchblox.com/security/data/fix/linux/alas2023-2026-2123.md) | Aug 31, 2026 | | Linux | python3.13-freethreading-debug amzn 2023 | 3.13.15-1.amzn2023.0.1 | [ALAS2023-2026-2123](https://patchblox.com/security/data/fix/linux/alas2023-2026-2123.md) | Aug 31, 2026 | | Linux | python3.13-idle amzn 2023 | 3.13.15-1.amzn2023.0.1 | [ALAS2023-2026-2123](https://patchblox.com/security/data/fix/linux/alas2023-2026-2123.md) | Aug 31, 2026 | | Linux | python3.13-libs amzn 2023 | 3.13.15-1.amzn2023.0.1 | [ALAS2023-2026-2123](https://patchblox.com/security/data/fix/linux/alas2023-2026-2123.md) | Aug 31, 2026 | | Linux | python3.13-test amzn 2023 | 3.13.15-1.amzn2023.0.1 | [ALAS2023-2026-2123](https://patchblox.com/security/data/fix/linux/alas2023-2026-2123.md) | Aug 31, 2026 | | Linux | python3.13-tkinter amzn 2023 | 3.13.15-1.amzn2023.0.1 | [ALAS2023-2026-2123](https://patchblox.com/security/data/fix/linux/alas2023-2026-2123.md) | Aug 31, 2026 | | Linux | python3.14 Debian 14 | 3.14.7-1 | [DEBIAN-CVE-2026-18503](https://patchblox.com/security/data/fix/linux/debian-cve-2026-18503.md) | Aug 18, 2026 | | Linux | python3.14 amzn 2023 | 3.14.7-1.amzn2023.0.1 | [ALAS2023-2026-2122](https://patchblox.com/security/data/fix/linux/alas2023-2026-2122.md) | Aug 31, 2026 | | Linux | python3.14-debug amzn 2023 | 3.14.7-1.amzn2023.0.1 | [ALAS2023-2026-2122](https://patchblox.com/security/data/fix/linux/alas2023-2026-2122.md) | Aug 31, 2026 | | Linux | python3.14-debuginfo amzn 2023 | 3.14.7-1.amzn2023.0.1 | [ALAS2023-2026-2122](https://patchblox.com/security/data/fix/linux/alas2023-2026-2122.md) | Aug 31, 2026 | | Linux | python3.14-debugsource amzn 2023 | 3.14.7-1.amzn2023.0.1 | [ALAS2023-2026-2122](https://patchblox.com/security/data/fix/linux/alas2023-2026-2122.md) | Aug 31, 2026 | | Linux | python3.14-devel amzn 2023 | 3.14.7-1.amzn2023.0.1 | [ALAS2023-2026-2122](https://patchblox.com/security/data/fix/linux/alas2023-2026-2122.md) | Aug 31, 2026 | | Linux | python3.14-freethreading amzn 2023 | 3.14.7-1.amzn2023.0.1 | [ALAS2023-2026-2122](https://patchblox.com/security/data/fix/linux/alas2023-2026-2122.md) | Aug 31, 2026 | | Linux | python3.14-freethreading-debug amzn 2023 | 3.14.7-1.amzn2023.0.1 | [ALAS2023-2026-2122](https://patchblox.com/security/data/fix/linux/alas2023-2026-2122.md) | Aug 31, 2026 | | Linux | python3.14-freethreading-devel amzn 2023 | 3.14.7-1.amzn2023.0.1 | [ALAS2023-2026-2122](https://patchblox.com/security/data/fix/linux/alas2023-2026-2122.md) | Aug 31, 2026 | | Linux | python3.14-freethreading-idle amzn 2023 | 3.14.7-1.amzn2023.0.1 | [ALAS2023-2026-2122](https://patchblox.com/security/data/fix/linux/alas2023-2026-2122.md) | Aug 31, 2026 | | Linux | python3.14-freethreading-libs amzn 2023 | 3.14.7-1.amzn2023.0.1 | [ALAS2023-2026-2122](https://patchblox.com/security/data/fix/linux/alas2023-2026-2122.md) | Aug 31, 2026 | | Linux | python3.14-freethreading-test amzn 2023 | 3.14.7-1.amzn2023.0.1 | [ALAS2023-2026-2122](https://patchblox.com/security/data/fix/linux/alas2023-2026-2122.md) | Aug 31, 2026 | | Linux | python3.14-freethreading-tkinter amzn 2023 | 3.14.7-1.amzn2023.0.1 | [ALAS2023-2026-2122](https://patchblox.com/security/data/fix/linux/alas2023-2026-2122.md) | Aug 31, 2026 | | Linux | python3.14-idle amzn 2023 | 3.14.7-1.amzn2023.0.1 | [ALAS2023-2026-2122](https://patchblox.com/security/data/fix/linux/alas2023-2026-2122.md) | Aug 31, 2026 | | Linux | python3.14-libs amzn 2023 | 3.14.7-1.amzn2023.0.1 | [ALAS2023-2026-2122](https://patchblox.com/security/data/fix/linux/alas2023-2026-2122.md) | Aug 31, 2026 | | Linux | python3.14-test amzn 2023 | 3.14.7-1.amzn2023.0.1 | [ALAS2023-2026-2122](https://patchblox.com/security/data/fix/linux/alas2023-2026-2122.md) | Aug 31, 2026 | | Linux | python3.14-tkinter amzn 2023 | 3.14.7-1.amzn2023.0.1 | [ALAS2023-2026-2122](https://patchblox.com/security/data/fix/linux/alas2023-2026-2122.md) | Aug 31, 2026 | | Linux | python3.15 Debian 14 | 3.15.0~rc1-1 | [DEBIAN-CVE-2026-18503](https://patchblox.com/security/data/fix/linux/debian-cve-2026-18503.md) | Aug 18, 2026 | | Linux | python313 sles 15.7 | 3.13.15-150700.4.56.1 | [SUSE-SU-2026:4401-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4401-1.md) | Sep 30, 2026 | | Linux | python313-core sles 15.7 | 3.13.15-150700.4.56.1 | [SUSE-SU-2026:4401-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4401-1.md) | Sep 30, 2026 | ## No fix yet | Platform | Product | Status | |---|---|---| | Windows apps | Python 2 | no-fix | | Windows apps | Python 3.10 | no-fix | | Windows apps | Python 3.11 | no-fix | | Windows apps | Python 3.12 | no-fix | | Windows apps | Python 3.5 | no-fix | | Windows apps | Python 3.6 | no-fix | | Windows apps | Python 3.7 | no-fix | | Windows apps | Python 3.8 | no-fix | | Windows apps | Python 3.9 | no-fix | | macOS | Python3 | no-fix | --- Data as of 2026-11-08T06:59:42Z UTC. 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