Vulnerability · Published Jun 2, 2026 · Assigned by Go
CVE-2026-42504Quadratic complexity in WordDecoder.DecodeHeader in mime
High 7.5
In plain English
A high-severity security flaw in mime from Go standard library. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 47% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Severity (CVSS 3.1)7.5High
Exploit odds (30 days)0.6%top 53.2% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
Decoding a maliciously-crafted MIME header containing many invalid encoded-words can consume excessive CPU.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:8 | delve | 1.26.1-1.module_el8.10.0+4223+bd807c2e | ALSA-2026:38995 |
| AlmaLinux:10 | go-fdo-client | 1.0.0-4.el10_2.7 | ALSA-2026:62577 |
| AlmaLinux:10 | go-toolset | 1.26.4-1.el10_2.alma.1 | ALSA-2026:29980 |
| AlmaLinux:8 | go-toolset | 1.26.5-1.module_el8.10.0+4223+bd807c2e | ALSA-2026:38995 |
| AlmaLinux:9 | go-toolset | 1.26.4-1.el9_8 | ALSA-2026:29981 |
| AlmaLinux:10 | golang | 1.26.4-1.el10_2.alma.1 | ALSA-2026:29980 |
| AlmaLinux:8 | golang | 1.26.5-1.module_el8.10.0+4223+bd807c2e | ALSA-2026:38995 |
| AlmaLinux:9 | golang | 1.26.4-1.el9_8 | ALSA-2026:29981 |
| AlmaLinux:10 | golang-bin | 1.26.4-1.el10_2.alma.1 | ALSA-2026:29980 |
| AlmaLinux:8 | golang-bin | 1.26.5-1.module_el8.10.0+4223+bd807c2e | ALSA-2026:38995 |
| AlmaLinux:9 | golang-bin | 1.26.4-1.el9_8 | ALSA-2026:29981 |
| AlmaLinux:10 | golang-docs | 1.26.4-1.el10_2.alma.1 | ALSA-2026:29980 |
| AlmaLinux:8 | golang-docs | 1.26.5-1.module_el8.10.0+4223+bd807c2e | ALSA-2026:38995 |
| AlmaLinux:9 | golang-docs | 1.26.4-1.el9_8 | ALSA-2026:29981 |
| AlmaLinux:10 | golang-misc | 1.26.4-1.el10_2.alma.1 | ALSA-2026:29980 |
| AlmaLinux:8 | golang-misc | 1.26.5-1.module_el8.10.0+4223+bd807c2e | ALSA-2026:38995 |
| AlmaLinux:9 | golang-misc | 1.26.4-1.el9_8 | ALSA-2026:29981 |
| AlmaLinux:10 | golang-race | 1.26.4-1.el10_2.alma.1 | ALSA-2026:29980 |
| AlmaLinux:8 | golang-race | 1.26.5-1.module_el8.10.0+4223+bd807c2e | ALSA-2026:38995 |
| AlmaLinux:9 | golang-race | 1.26.4-1.el9_8 | ALSA-2026:29981 |
| AlmaLinux:10 | golang-src | 1.26.4-1.el10_2.alma.1 | ALSA-2026:29980 |
| AlmaLinux:8 | golang-src | 1.26.5-1.module_el8.10.0+4223+bd807c2e | ALSA-2026:38995 |
| AlmaLinux:9 | golang-src | 1.26.4-1.el9_8 | ALSA-2026:29981 |
| AlmaLinux:10 | golang-tests | 1.26.4-1.el10_2.alma.1 | ALSA-2026:29980 |
| AlmaLinux:8 | golang-tests | 1.26.5-1.module_el8.10.0+4223+bd807c2e | ALSA-2026:38995 |
| AlmaLinux:9 | golang-tests | 1.26.4-1.el9_8 | ALSA-2026:29981 |
| AlmaLinux:10 | grafana | 10.2.6-28.el10_2.5 | ALSA-2026:63022 |
| AlmaLinux:8 | grafana | 9.2.10-33.el8_10 | ALSA-2026:62407 |
| AlmaLinux:9 | grafana | 10.2.6-23.el9_8.3 | ALSA-2026:62406 |
| AlmaLinux:10 | grafana-pcp | 5.3.0-8.el10_2.1 | ALSA-2026:63119 |
| AlmaLinux:8 | grafana-pcp | 5.1.1-18.el8_10 | ALSA-2026:63124 |
| AlmaLinux:10 | grafana-selinux | 10.2.6-28.el10_2.5 | ALSA-2026:63022 |
| AlmaLinux:8 | grafana-selinux | 9.2.10-33.el8_10 | ALSA-2026:62407 |
| AlmaLinux:9 | grafana-selinux | 10.2.6-23.el9_8.3 | ALSA-2026:62406 |
| AlmaLinux:10 | ipp-usb | 0.9.27-7.el10_2.3 | ALSA-2026:62631 |
| AlmaLinux:10 | opentelemetry-collector | 0.152.1-2.el10_2 | ALSA-2026:65116 |
| AlmaLinux:9 | opentelemetry-collector | 0.152.1-2.el9_8 | ALSA-2026:65117 |
| AlmaLinux:8 | osbuild-composer | 101.5-3.el8_10.alma.1 | ALSA-2026:67148 |
| AlmaLinux:9 | osbuild-composer | 165.1-4.el9_8.1.alma.1 | ALSA-2026:65153 |
| AlmaLinux:8 | osbuild-composer-core | 101.5-3.el8_10.alma.1 | ALSA-2026:67148 |
| AlmaLinux:9 | osbuild-composer-core | 165.1-4.el9_8.1.alma.1 | ALSA-2026:65153 |
| AlmaLinux:8 | osbuild-composer-worker | 101.5-3.el8_10.alma.1 | ALSA-2026:67148 |
| AlmaLinux:9 | osbuild-composer-worker | 165.1-4.el9_8.1.alma.1 | ALSA-2026:65153 |
| AlmaLinux:10 | yggdrasil | 0.4.9.2-1.el10_2.3 | ALSA-2026:69308 |
| AlmaLinux:10 | yggdrasil-devel | 0.4.9.2-1.el10_2.3 | ALSA-2026:69308 |
| Alpine:v3.24 | go | 1.26.8-r0 | ALPINE-CVE-2026-42504 |
| Debian:12 | golang-1.19 | no fix listed | DEBIAN-CVE-2026-42504 |
| Debian:13 | golang-1.24 | no fix listed | DEBIAN-CVE-2026-42504 |
| Debian:14 | golang-1.26 | 1.26.4-1 | DEBIAN-CVE-2026-42504 |
| Go | stdlib | 1.25.11, 1.26.4 | GO-2026-5038 |
| Rocky Linux:10 | golang-github-openprinting-ipp-usb | 0:0.9.27-7.el10_2.3 | RLSA-2026:62631 |
| Rocky Linux:10 | grafana-pcp | 0:5.3.0-8.el10_2.1 | RLSA-2026:63119 |
| Rocky Linux:8 | grafana-pcp | 0:5.1.1-18.el8_10 | RLSA-2026:63124 |
| Rocky Linux:10 | image-builder | 0:52.1-1.el10_2.2.rocky.0.1 | RLSA-2026:65534 |
| Rocky Linux:9 | image-builder | 0:52.1-1.el9_8.2 | RLSA-2026:65886 |
| Rocky Linux:10 | opentelemetry-collector | 0:0.152.1-2.el10_2 | RLSA-2026:65116 |
| Rocky Linux:9 | opentelemetry-collector | 0:0.152.1-2.el9_8 | RLSA-2026:65117 |
| Rocky Linux:10 | osbuild-composer | 0:165.1-3.el10_2.2.rocky.0.1 | RLSA-2026:65895 |
| Rocky Linux:8 | osbuild-composer | 0:101.5-3.el8_10.rocky.0.6 | RLSA-2026:67148 |
| Rocky Linux:9 | osbuild-composer | 0:165.1-4.el9_8.1.rocky.0.1 | RLSA-2026:65153 |
| Rocky Linux:10 | yggdrasil | 0:0.4.9.2-1.el10_2.3 | RLSA-2026:69308 |
| Ubuntu:22.04:LTS | golang-1.24 | no fix listed | UBUNTU-CVE-2026-42504 |
| Ubuntu:24.04:LTS | golang-1.24 | no fix listed | UBUNTU-CVE-2026-42504 |
| Ubuntu:25.10 | golang-1.24 | no fix listed | UBUNTU-CVE-2026-42504 |
| Ubuntu:26.04:LTS | golang-1.24 | no fix listed | UBUNTU-CVE-2026-42504 |
| Ubuntu:22.04:LTS | golang-1.25 | no fix listed | UBUNTU-CVE-2026-42504 |
| Ubuntu:24.04:LTS | golang-1.25 | no fix listed | UBUNTU-CVE-2026-42504 |
| Ubuntu:25.10 | golang-1.25 | no fix listed | UBUNTU-CVE-2026-42504 |
| Ubuntu:26.04:LTS | golang-1.25 | no fix listed | UBUNTU-CVE-2026-42504 |
| Ubuntu:22.04:LTS | golang-1.26 | no fix listed | UBUNTU-CVE-2026-42504 |
| Ubuntu:24.04:LTS | golang-1.26 | no fix listed | UBUNTU-CVE-2026-42504 |
| Ubuntu:26.04:LTS | golang-1.26 | no fix listed | UBUNTU-CVE-2026-42504 |
| Ubuntu:26.10 | golang-1.26 | no fix listed | UBUNTU-CVE-2026-42504 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Go standard library | mime | 0 – before 1.25.111.26.0-0 – before 1.26.4 |
Weakness: CWE-407 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H