CVE-2026-18503
published 2026-08-10CVE-2026-18503: Attacker-controlled CSV samples can trigger super-linear regular-expression work during dialect sniffing and consume significant CPU when applications pass…
PriorityP410low2.4CVSS 4.0
AVLACLATNPRLUIPVCNVINVALSCNSINSANEXCRXIRXARXMAVXMACXMATXMPRXMUIXMVCXMVIXMVAXMSCXMSIXMSAXSXAUXRXVXREXUX
EPSS
0.12%
1.7th 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().
Affected
16 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| ansible-automation-platform | bootc-automation-portal-rhel9 | — | — |
| container-native-virtualization | ocp-virt-validation-checkup-rhel9 | — | — |
| debian | python3.9 | — | — |
| devspaces | code-rhel9 | — | — |
| exploit-intelligence-tech-preview | vulnerability-analysis-rhel9 | — | — |
| python | python | — | — |
| python_software_foundation | cpython | < 3.10.21 | 3.10.21 |
| python_software_foundation | cpython | >= 3.11.0 < 3.11.16 | 3.11.16 |
| python_software_foundation | cpython | >= 3.12.0 < 3.12.14 | 3.12.14 |
| python_software_foundation | cpython | >= 3.13.0 < 3.13.15 | 3.13.15 |
| python_software_foundation | cpython | >= 3.14.0 < 3.14.7 | 3.14.7 |
| python_software_foundation | cpython | >= 3.15.0a1 < 3.15.0rc1 | 3.15.0rc1 |
| python_software_foundation | cpython | >= 3.16.0a1 < 3.16.0 | 3.16.0 |
| rhel-cla | rhel-knowledge-bridge-rhel10 | — | — |
| rhelai3 | bootc-cuda-rhel9 | — | — |
| rhoai | odh-workbench-codeserver-datascience-cpu-py312-rhel9 | — | — |
CVSS provenance
nvdv4.02.4LOWCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:L/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
vendor_redhat2.4LOW
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GHSA
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().
ghsa_unreviewed·2026-08-10
CVE-2026-18503 [LOW] CWE-1176 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().
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().
Red Hat
python: Python: Denial of Service via super-linear regular expression work in csv.Sniffer.sniff()
vendor_redhat·2026-08-10·CVSS 2.4
CVE-2026-18503 [LOW] CWE-1333 python: Python: Denial of Service via super-linear regular expression work in csv.Sniffer.sniff()
python: Python: Denial of Service via super-linear regular expression work in csv.Sniffer.sniff()
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().
A flaw was found in the `csv.Sniffer.sniff()` function within Python. An attacker can exploit this by providing specially crafted CSV samples, which can trigger super-linear regular-expression processing during dialect sniffing. This excessive processing consumes significant CPU resources, potentially leading to a Denial of Service (DoS) for applications that process unbounded input using this function.
Statement: Red Hat has evaluated this issue and determined it has a Low security impact. The csv
No detection rules found.
No public exploits indexed.
https://github.com/python/cpython/commit/063d4555c94ef412c731527dbf30193327f2ee82https://github.com/python/cpython/commit/476fb09cdb0d73e645849d98c610e7e5697ce7c9https://github.com/python/cpython/commit/89f29c760c02774b099ddd6863268eb13fa3946ahttps://github.com/python/cpython/commit/b09a67a20c464f8288c9f9a6b9c7082a74560024https://github.com/python/cpython/commit/b30c7fa9edd921a118f286e9f90f560777fa693bhttps://github.com/python/cpython/commit/fd78b565d7c326f96ae903ab945b47f35d829cf4https://github.com/python/cpython/issues/98820https://github.com/python/cpython/pull/153694https://mail.python.org/archives/list/[email protected]/thread/KQ7NBMCPAZJHRROQXJQE4GMXGLD5KHBS/
2026-08-10
Published