CVE-2026-18503: python software foundation cpython Inefficient CPU Computation
CVSS: 2.4v4.0LowAwaiting analysis
AliasesRHSA-2026:57010UBUNTU-CVE-2026-18503DEBIAN-CVE-2026-18503CGA-5247-x43q-37jcCGA-76jh-7c7w-4hrhCGA-78pw-hfx9-9cp7CGA-gw6j-wrh5-2gfhCGA-q2w7-2q6f-49mhCGA-w5wg-294h-xw6g
Published 10-08-2026Last modified 14-10-2026
Vulnerability summary
CVE-2026-18503 is a low (CVSS 2.4) Inefficient CPU Computation vulnerability in python software foundation cpython. EPSS estimates a 0.12% chance of exploitation in the next 30 days, higher than 1.6% of scored vulnerabilities.
CVSS score
2.4/10
010
Low · v4.0 (CVE.org)EPSS score
0.12%
0%100%
Low · 0.00 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Advisory lineage
Upstream 0 · Downstream 11 · Related 8Timeline
- 10-08-2026PublishedVulnerability first disclosed.
- 14-10-2026Last modifiedVulnerability information updated.
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().
CVSS metrics
7 scores · 7 sources · 2 versionsLow 2.4Preferred score · CVE.org (CNA)
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:NSourcesAll 6 agree
- OSV · UbuntuEcosystem advisory · calculated2.4LowCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
- OSV · DebianEcosystem advisory · calculated2.4LowCVSS: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
- OSV · WolfiEcosystem advisory · calculated2.4LowCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
- OSV · ChainguardEcosystem advisory · calculated2.4LowCVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
- NVDNIST2.4LowCVSS: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
Low 2.8Preferred score · OSV · Red hat (Ecosystem advisory) · calculated from vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:N/I:N/A:LSourcesSingle source
EPSS trend
Probability
0.12%
Chance of exploitation in the next 30 days
Percentile
2%
Versus all other CVEs
30-day change
0.00 pp
From 0.12% on 20-09-2026
20-09-202620-10-2026
EPSS score0.12%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Ubuntu11 products
- python2.7All versions (No fix recorded)
- python3.10All versions (No fix recorded)
- python3.11All versions (No fix recorded)
- python3.12All versions (No fix recorded)
- python3.14All versions (No fix recorded)
Redhat7 products
- python3.10< 0:3.10.21-1.hum1
- python3.10-debug< 0:3.10.21-1.hum1
- python3.10-devel< 0:3.10.21-1.hum1
- python3.10-idle< 0:3.10.21-1.hum1
- python3.10-libs< 0:3.10.21-1.hum1
Debian5 products
- pypy3All versions (No fix recorded)
- python3.11< 3.11.2-6+deb12u9
- python3.13All versions (No fix recorded) | < 3.13.15-1
- python3.14< 3.14.7-1
- python3.15< 3.15.0~rc1-1
Chainguard3 products
- python-3.10< 3.10.21-r0
- python-3.11< 3.11.16-r0
- python-3.12< 3.12.14-r0
Wolfi3 products
- python-3.10< 3.10.21-r0
- python-3.11< 3.11.16-r0
- python-3.12< 3.12.14-r0
Python software foundation1 product
- cpython< 3.10.21 | ≥ 3.11.0, < 3.11.16 | ≥ 3.12.0, < 3.12.14 | ≥ 3.13.0, < 3.13.15 | ≥ 3.14.0, < 3.14.7 | ≥ 3.15.0a1, < 3.15.0rc1 | ≥ 3.16.0a1, < 3.16.0
6 vendors · 30 products
References
21 links- mail.python.org/archives/list/security-announce@python.org/thread/KQ7NBMCPAZJHRROQXJQE4GMXGLD5KHBS/Vendor AdvisoryARTICLEREPORTAdvisory
Show all 21 references
- images.redhat.comARTICLE
- github.com/python/cpythonPACKAGE