CVE-2026-28356ReDoS in multipart 1.3.0 - `parse_options_header()`
Updated under an hour ago ()
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It affects defnull multipart and 7 other products. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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multipart is a fast multipart/form-data parser for python. Prior to 1.2.2, 1.3.1 and 1.4.0-dev, the parse_options_header() function in multipart.py uses a regular expression with an ambiguous alternation, which can cause exponential backtracking (ReDoS) when parsing maliciously crafted HTTP or multipart segment headers. This can be abused for denial of service (DoS) attacks against web applications using this library to parse request headers or multipart/form-data streams. The issue is fixed in 1.2.2, 1.3.1 and 1.4.0-dev.
- CVSS
- 7.5 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- Weakness (CWE)
- CWE-1333
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Deferred
- Record last updated
- Aug 24, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
defnull multipart defnull:multipart (from the name) | from 1.3.0, < 1.3.1; before 1.2.2 | CNA record |
Red Hat Red Hat AI Inference Server 3.2 redhat:ai_inference_server | from 1774351144 not affected | CISA ADP |
Red Hat Red Hat OpenShift AI 2.25 redhat:openshift_ai | from 1776247907 not affected | CISA ADP |
Red Hat Lightspeed Core redhat:lightspeed_core | All versions | CISA ADP |
Red Hat OpenShift Lightspeed redhat:openshift_lightspeed | Versions not stated | CISA ADP |
Red Hat Red Hat Ansible Automation Platform 2 redhat:ansible_automation_platform | 2 | CISA ADP |
Red Hat Red Hat Enterprise Linux AI (RHEL AI) 3 redhat:enterprise_linux_ai | 3 | CISA ADP |
Red Hat Red Hat Satellite 6 redhat:satellite | 6 | CISA ADP |
References
- https://github.com/defnull/multipart/security/advisories/GHSA-p2m9-wcp5-6qw3x-refsource-confirm
- https://access.redhat.com/errata/RHSA-2026:10184
- https://access.redhat.com/errata/RHSA-2026:37275
- https://access.redhat.com/errata/RHSA-2026:42644
- https://access.redhat.com/errata/RHSA-2026:5809
- https://access.redhat.com/errata/RHSA-2026:6761
- https://access.redhat.com/errata/RHSA-2026:6762
- https://access.redhat.com/security/cve/CVE-2026-28356
- https://bugzilla.redhat.com/show_bug.cgi?id=2447059
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-28356.json
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.