Description
The Pallets Project flask version Before 0.12.3 contains a CWE-20: Improper Input Validation vulnerability in flask that can result in Large amount of memory usage possibly leading to denial of service. This attack appear to be exploitable via Attacker provides JSON data in incorrect encoding. This vulnerability appears to have been fixed in 0.12.3. NOTE: this may overlap CVE-2019-1010083.
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 | flask | 1.0.2-1 | — |
| Debian 13 | flask | 1.0.2-1 | — |
| Debian 12 | flask | 1.0.2-1 | — |
| Debian 8 | flask | 0.10.1-2+deb8u1 | DLA-1892-1 |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 18.04 LTS | flask | 0.12.2-3ubuntu0.1 | USN-4378-1 |
| Ubuntu 16.04 LTS | flask | 0.10.1-2ubuntu0.1 | USN-4378-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 14.04 LTS | flask | 0.10.1-2ubuntu0.1~esm1 | USN-4378-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Red Hat Rhel Extras Other 7 | python-flask | 1:0.10.1-5.el7_7 | RHSA-2020:0870 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 | python-Flask | 0.12.4-3.3.26 | SUSE-SU-2019:0657-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Leap 15.0 | python-Flask | 0.12.4-lp150.2.3.1 | openSUSE-SU-2019:1112-1 |
Affected packages
| Ecosystem | Package | Affected | Fixed | Record |
|---|---|---|---|---|
| PyPI | flask | < 0.12.3 | 0.12.3 | GHSA-562c-5r94-xh97 |
Advisories 5
- USN-4378-1 flask vulnerability Ubuntu Security Notices (USN) · Jun 29, 2026
- DLA-1892-1 flask - security update Debian Security (DSA / DLA) · Mar 9, 2026
- openSUSE-SU-2019:1112-1 Security update for python-Flask SUSE / openSUSE Security Updates · Feb 4, 2026
- SUSE-SU-2019:0657-1 Security update for python-Flask SUSE / openSUSE Security Updates · Feb 4, 2026
- RHSA-2020:0870 Red Hat Security Advisory: python-flask security update Red Hat Security Advisories (RHSA) · Nov 22, 2025