Description
Marshmallow is a lightweight library for converting complex objects to and from simple Python datatypes. In versions from 3.0.0rc1 to before 3.26.2 and from 4.0.0 to before 4.1.2, Schema.load(data, many=True) is vulnerable to denial of service attacks. A moderately sized request can consume a disproportionate amount of CPU time. This issue has been patched in version 3.26.2 and 4.1.2.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| marshmallow-code | marshmallow | >= 3.0.0rc1, < 3.26.2, >= 4.0.0, < 4.1.2 | — |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | python-marshmallow | 3.26.2-0.1 | — |
| Debian 13 | python-marshmallow | 3.26.2-0+deb13u1 | — |
| Debian 12 | python-marshmallow | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | python-marshmallow | No fix yet | — |
| Ubuntu 25.10 | python-marshmallow | No fix yet | — |
Show 5 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 26.04 LTS | python-marshmallow | 3.26.1-0.4ubuntu0.1~esm1 | USN-8225-1 |
| Ubuntu Pro 24.04 LTS | python-marshmallow | 3.20.1-1.1ubuntu0.1~esm1 | USN-8225-1 |
| Ubuntu Pro 22.04 LTS | python-marshmallow | 3.13.0-1ubuntu0.1~esm1 | USN-8225-1 |
| Ubuntu Pro 20.04 LTS | python-marshmallow | 3.4.0-1ubuntu0.1~esm1 | USN-8225-1 |
| Ubuntu Pro 18.04 LTS | python-marshmallow | 3.0.0b3-1ubuntu0.1~esm1 | USN-8225-1 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | python-marshmallow | 3.20.2-150400.9.10.1 | SUSE-SU-2026:0226-1 |
| SLES 15 SP6 | python-marshmallow | 3.20.2-150400.9.10.1 | SUSE-SU-2026:0226-1 |
| SLES 15 SP5 | python-marshmallow | 3.20.2-150400.9.10.1 | SUSE-SU-2026:0226-1 |
| SLES 15 SP4 | python-marshmallow | 3.20.2-150400.9.10.1 | SUSE-SU-2026:0226-1 |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | python-marshmallow | 3.20.2-160000.3.1 | SUSE-SU-2026:20130-1 |
| SLES 16.0 | python-marshmallow | 3.20.2-160000.3.1 | SUSE-SU-2026:20130-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | python-marshmallow | 3.26.2-1.1 | openSUSE-SU-2026:10003-1 |
| openSUSE Leap 16.0 | python-marshmallow | 3.20.2-160000.3.1 | openSUSE-SU-2026:20087-1 |
| openSUSE Leap 15.6 | python-marshmallow | 3.20.2-150400.9.10.1 | SUSE-SU-2026:0226-1 |
Wolfi
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Wolfi rolling | airflow-3 +3 | 3.1.5-r1 | — |
| Wolfi rolling | ggshield | 1.49.0-r1 | — |
| Wolfi rolling | open-webui +1 | 0.6.41-r1 | — |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | marshmallow | >= 3.0.0rc1, < 3.26.2 | 3.26.2 | GHSA-428g-f7cq-pgp5 |
| PyPI | marshmallow | >= 4.0.0, < 4.1.2 | 4.1.2 | GHSA-428g-f7cq-pgp5 |
| PyPI | marshmallow | >= 3.0.0rc1, < 3.26.2 · >= 4.0.0, < 4.1.2 | 3.26.2, 4.1.2 | PYSEC-2026-1605 |
Advisories 6
- WID-SEC-2026-2451 Oracle Siebel CRM: Mehrere Schwachstellen BSI CERT-Bund (WID) · Sep 2, 2026
- USN-8225-1 python-marshmallow vulnerabilities Ubuntu Security Notices (USN) · Apr 30, 2026
- openSUSE-SU-2026:20087-1 Security update for python-marshmallow SUSE / openSUSE Security Updates · Mar 23, 2026
- openSUSE-SU-2026:10003-1 python311-marshmallow-3.26.2-1.1 on GA media SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2026:20130-1 Security update for python-marshmallow SUSE / openSUSE Security Updates · Mar 23, 2026
- SUSE-SU-2026:0226-1 Security update for python-marshmallow SUSE / openSUSE Security Updates · Mar 23, 2026