Super-linear CPU usage for unbounded input to csv.Sniffer.sniff()
Priority LOW 11CWE-1176Published · Updated
Key facts
- Attack vector
- Local
- Privileges required
- Low
- User interaction
- Passive
- Attack complexity
- Low
- Attack requirements
- None
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · Low
- Fix status
- Partial Red Hat: 1 fixed, 12 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat.
Summary
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().
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00119 1st percentileScored 2026-11-07
Fix Partial CPython (Python Software Foundation): 3.10.21, 3.11.16, 3.12.14 +4Red Hat: 5 advisoriesRed Hat: 1 fixed, 12 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Python Software Foundation | CPython | before 3.10.21; 3.11.0 to before 3.11.16; 3.12.0 to before 3.12.14; 3.13.0 to before 3.13.15; 3.14.0 to before 3.14.7; 3.15.0a1 to before 3.15.0rc1; 3.16.0a1 to before 3.16.0 | 3.10.21, 3.11.16, 3.12.14, 3.13.15, 3.14.7, 3.15.0rc1, 3.16.0 | Patch available | CNA |
- CPython VendorPython Software Foundation Affected before 3.10.21; 3.11.0 to before 3.11.16; 3.12.0 to before 3.12.14; 3.13.0 to before 3.13.15; 3.14.0 to before 3.14.7; 3.15.0a1 to before 3.15.0rc1; 3.16.0a1 to before 3.16.0 Fixed in 3.10.21, 3.11.16, 3.12.14, 3.13.15, 3.14.7, 3.15.0rc1, 3.16.0 Patch available CNA
CPE names Threatist (inferred) · 1
Inferred from how NVD named this product before; not given by a source.
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:python:python:*:*:*:*:*:*:*:* | — | — | python-pillow |
- cpe:2.3:a:python:python:*:*:*:*:*:*:*:* Versions — — ·python-pillow
Remediation
- Fix · CNA CPython (Python Software Foundation) Fixed in 3.10.21, 3.11.16, 3.12.14, 3.13.15, 3.14.7, 3.15.0rc1, 3.16.0
Red Hat 5 advisories
- RHSA-2026:58420 Released 2026-08-21 · Red Hat rating ModerateRed Hat Hardened Images RPMs Security Update
- Red Hat Hardened Images python3.12-3.12.14-1.hum1@aarch64, python3.12-3.12.14-1.hum1@src, python3.12-3.12.14-1.hum1@x86_64 +12
- RHSA-2026:57660 Released 2026-08-20 · Red Hat rating ModerateRed Hat Hardened Images RPMs Security Update
- Red Hat Hardened Images python3.11-3.11.16-1.hum1@aarch64, python3.11-3.11.16-1.hum1@src, python3.11-3.11.16-1.hum1@x86_64 +12
- RHSA-2026:57010 Released 2026-08-19 · Red Hat rating LowRed Hat Hardened Images RPMs bug fix and enhancement update
- Red Hat Hardened Images python3.10-3.10.21-1.hum1@aarch64, python3.10-3.10.21-1.hum1@src, python3.10-3.10.21-1.hum1@x86_64 +12
Show 2 more Red Hat advisories
- RHSA-2026:54554 Released 2026-08-13 · Red Hat rating ImportantRed Hat Hardened Images RPMs Security Update
- Red Hat Hardened Images python3.13-3.13.15-1.hum1@aarch64, python3.13-3.13.15-1.hum1@src, python3.13-3.13.15-1.hum1@x86_64 +16
- RHSA-2026:54534 Released 2026-08-13 · Red Hat rating ImportantRed Hat Hardened Images RPMs Security Update
- Red Hat Hardened Images python-unversioned-command-3.14.7-1.hum1@noarch@public-hummingbird-aarch64-rpms, python-unversioned-command-3.14.7-1.hum1@noarch@public-hummingbird-x86_64-rpms, python3-3.14.7-1.hum1@aarch64 +28
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Exploit Intelligence | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 6 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 7 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 8 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux AI (RHEL AI) 3 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux command line assistant | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Dev Spaces | Affected | No fix yet: Fix deferred |
| Red Hat OpenShift Virtualization 4 | Affected | No fix yet: Fix deferred |
| Self-service automation portal 2 | Affected | No fix yet: Fix deferred |
| Red Hat Hardened Images | Fixed | RHSA-2026:54534, RHSA-2026:54554, RHSA-2026:57010, RHSA-2026:57660, RHSA-2026:58420 |
Timeline
- 2026-10-02 Threatist record created from CVE-2026-18503
- 2026-10-03 Alias added: GHSA-2345-wr3r-cxf2
- 2026-10-14 Fix available: Python Software Foundation/[email protected] · CNA
References
Patch 7
- https://github.com/python/cpython/pull/153694
- https://github.com/python/cpython/commit/063d4555c94ef412c731527dbf30193327f2ee82
- https://github.com/python/cpython/commit/476fb09cdb0d73e645849d98c610e7e5697ce7c9
- https://github.com/python/cpython/commit/89f29c760c02774b099ddd6863268eb13fa3946a
- https://github.com/python/cpython/commit/b30c7fa9edd921a118f286e9f90f560777fa693b
- https://github.com/python/cpython/commit/b09a67a20c464f8288c9f9a6b9c7082a74560024
- https://github.com/python/cpython/commit/fd78b565d7c326f96ae903ab945b47f35d829cf4
Advisory 1
More Python Software Foundation vulnerabilities
- TI-2024-07037 Quadratic complexity parsing cookies with backslashes CVSS 3.1HIGH 7.5
- TI-2024-11791 Bypass extraction filter to modify file metadata outside extraction directory CVSS 3.1MEDIUM 5.3
- TI-2024-00411 Quoted zip-bomb protection for zipfile CVSS 3.1MEDIUM 6.2
- TI-2026-13296 `HTTPPasswordMgr` can send saved HTTPS credentials via HTTP because of incorrect scheme matching CVSS 4.0MEDIUM 6.0
- TI-2024-06422 Email header injection due to unquoted newlines CVSS 3.1MEDIUM 5.5
- TI-2026-04606 Possible to hijack modules in current working directory CVSS 4.0MEDIUM 5.6
Sources
- CVE-2026-18503 · CVE Program
- CVE-2026-18503 · NVD
- FIRST EPSS
- GHSA-2345-wr3r-cxf2 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-18503 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences