Zip Bomb Denial of Service via Unrestricted Archive Decompression

published 2026-03-26 7 mo ago modified 2026-06-25 4 mo ago also GHSA-vhgh-g7x8-4rx8 , GO-2026-5663 , EUVD-2026-16242

cvss: 6.5; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.4%; EPSS 0.4% chance of exploitation in 30 days, percentile 29%
public exploits: 0; none known

Mattermost versions 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to validate decompressed archive entry sizes during file extraction which allows authenticated users with file upload permissions to cause a denial of service via crafted zip archives containing highly compressed entries (zip bombs) that exhaust server memory.. Mattermost Advisory ID: MMSA-2026-00598

Patch / fix

fixed in 3 distros 1

go github.com/mattermost/mattermost/server/v8 8.0.0-20260217110922-b7d4a1f1f59b, 10.11.12, 11.2.4, 11.3.2, 11.4.1
go github.com/mattermost/mattermost-server 10.11.12+incompatible, 11.2.4+incompatible, 11.3.2+incompatible, 11.4.1+incompatible
Mattermost Mattermost 10.11.12, 11.2.4, 11.3.2, 11.4.1, 11.5.0

govulncheck-vulndb openSUSE Leap 16.0 0.0.20260723T184607-160000.1.1

opensuse advisories openSUSE-SU-2026:21483-1

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-3114 updated 2026-03-26 cvss 6.5

Mattermost: Mattermost: Denial of Service via crafted zip archives

Red Hat All currently supported Red Hat products
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 7 mo ago (2026-03-26)

Exploit prediction

0.36% chance of exploitation in the next 30 days, higher than 29% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
GitHub	3.1	6.5	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem	package	affected	fixed in
go	github.com/mattermost/mattermost/server/v8	>=11.4.0, <11.4.1 >=11.3.0, <11.3.2 >=11.2.0, <11.2.4 >=10.11.0, <10.11.12 >=8.0.0-20260105080200-d27a2195068d, <8.0.0-20260217110922-b7d4a1f1f59b	11.4.1 11.3.2 11.2.4 10.11.12 8.0.0-20260217110922-b7d4a1f1f59b
go	github.com/mattermost/mattermost-server	>=10.11.0+incompatible, <10.11.12+incompatible >=11.2.0+incompatible, <11.2.4+incompatible >=11.3.0+incompatible, <11.3.2+incompatible >=11.4.0+incompatible, <11.4.1+incompatible	10.11.12+incompatible 11.2.4+incompatible 11.3.2+incompatible 11.4.1+incompatible
go	github.com/mattermost/mattermost-server/v5	all versions	no fix listed
go	github.com/mattermost/mattermost-server/v6	all versions	no fix listed

Affected products

Mattermost Mattermost

Classification

Weakness

CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)

References

mattermost.com /security-updates
vendor-advisory, web
nvd.nist.gov /vuln/detail/CVE-2026-3114
advisory
github.com /mattermost/mattermost
package
github.com /advisories/GHSA-vhgh-g7x8-4rx8
advisory

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary