CPython misparses non-hex and negative integers in HTTP responses
Key facts
- Attack vector
- Network
- Privileges required
- High
- User interaction
- Passive
- Attack complexity
- Low
- Attack requirements
- Present
- Impact type
- —
- Confidentiality · integrity · availability
- None · None · None
- Fix status
- Partial Red Hat: 9 without a fix
Attack profile from CVSS 4.0 · CNA. Fix status from CNA and Red Hat.
Summary
CPython versions from 0 before 3.16.0 are affected. Response body and chunk size parsing accepts non-hex or negative integers, which is CWE-444 and can lead to misinterpreting HTTP response contents. A remote attacker with high privileges and user interaction can trigger this misinterpretation.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
Description from the CNA
Response body and chunk parsing would handle non-hex or negative integers incorrectly which could result in misinterpreting HTTP response contents.
Why it matters now
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 3.16.0 | 3.16.0 | Patch available | CNA |
- CPython VendorPython Software Foundation Affected before 3.16.0 Fixed in 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
Upgrade CPython to 3.16.0, which fixes this flaw. Red Hat lists Red Hat Enterprise Linux 6 with no fix planned, and lists Red Hat Enterprise Linux 7, Red Hat Enterprise Linux 8, Red Hat Enterprise Linux 9, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux AI (RHEL AI) 3, Red Hat Hardened Images, Red Hat OpenShift Virtualization 4 and Self-service automation portal 2 with no fix plan available.
Written with Claude Haiku 5.5 from the sources below · 2026-11-06
- Fix · CNA CPython (Python Software Foundation) Fixed in 3.16.0
Vendor assessments
Red Hat
Red Hat rating: Moderate. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| 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 |
| Red Hat Enterprise Linux AI (RHEL AI) 3 | Affected | No fix yet: Fix deferred |
| Red Hat Hardened Images | Affected | No fix yet |
| Red Hat OpenShift Virtualization 4 | Affected | No fix yet: Fix deferred |
| Self-service automation portal 2 | Affected | No fix yet: Fix deferred |
Timeline
- 2026-10-27 Threatist record created from CVE-2026-103995
- 2026-10-27 Alias added: GHSA-pp6r-vffx-rvqj
- 2026-10-28 2 new references · CNA
- 2026-11-04 CISA SSVC decision points changed
- 2026-11-06 Affected versions changed · Red Hat
- 2026-11-06 CVSS score added · Red Hat
References
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-2026-103995 · CVE Program
- CVE-2026-103995 · NVD
- FIRST EPSS
- GHSA-pp6r-vffx-rvqj · GitHub Advisory Database · CC BY 4.0
- CVE-2026-103995 · 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