CVE-2026-33811 Crash when handling long CNAME response in net
A double-free vulnerability in the Go net package's cgo DNS resolver allows attackers to cause a crash via long CNAME responses.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-33811?
CVE-2026-33811 is a high-severity memory corruption vulnerability in Golang Go, published on 7 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
When using LookupCNAME with the cgo DNS resolver, a very long CNAME response can trigger a double-free of C memory and a crash.
Which versions are affected by CVE-2026-33811?
2 open source packages ship an affected version, including golang and stdlib. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
golang Bitnami | All versions | 1.25.10, 1.26.3 |
stdlib Go | All versions | 1.25.10, 1.26.3 |
Linux distribution packages (23)
git-lfs AlmaLinux:10 | All versions | 3.7.1-5.el10_2.6 |
git-lfs AlmaLinux:8 | All versions | 3.4.1-12.el8_10 |
git-lfs AlmaLinux:9 | All versions | 3.7.1-4.el9_8.2 |
oci-seccomp-bpf-hook AlmaLinux:9 | All versions | 1.2.11-2.el9_8 |
git-lfs Red Hat:enterprise_linux:10.2 | All versions | 0:3.7.1-5.el10_2.6 |
git-lfs-debuginfo Red Hat:enterprise_linux:10.2 | All versions | 0:3.7.1-5.el10_2.6 |
git-lfs-debugsource Red Hat:enterprise_linux:10.2 | All versions | 0:3.7.1-5.el10_2.6 |
git-lfs Red Hat:enterprise_linux:8::appstream | All versions | 0:3.4.1-12.el8_10 |
git-lfs-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 0:3.4.1-12.el8_10 |
git-lfs-debugsource Red Hat:enterprise_linux:8::appstream | All versions | 0:3.4.1-12.el8_10 |
rhc Red Hat:enterprise_linux:8::appstream | All versions | 1:0.2.5-8.el8_10 |
rhc-debuginfo Red Hat:enterprise_linux:8::appstream | All versions | 1:0.2.5-8.el8_10 |
rhc-debugsource Red Hat:enterprise_linux:8::appstream | All versions | 1:0.2.5-8.el8_10 |
git-lfs Red Hat:enterprise_linux:9::appstream | All versions | 0:3.7.1-4.el9_8.2 |
git-lfs-debuginfo Red Hat:enterprise_linux:9::appstream | All versions | 0:3.7.1-4.el9_8.2 |
git-lfs-debugsource Red Hat:enterprise_linux:9::appstream | All versions | 0:3.7.1-4.el9_8.2 |
oci-seccomp-bpf-hook Red Hat:enterprise_linux:9::appstream | All versions | 0:1.2.11-2.el9_8 |
oci-seccomp-bpf-hook-debuginfo Red Hat:enterprise_linux:9::appstream | All versions | 0:1.2.11-2.el9_8 |
oci-seccomp-bpf-hook-debugsource Red Hat:enterprise_linux:9::appstream | All versions | 0:1.2.11-2.el9_8 |
git-lfs Rocky Linux:10 | All versions | 0:3.7.1-5.el10_2.6 |
git-lfs Rocky Linux:8 | All versions | 0:3.4.1-12.el8_10 |
git-lfs Rocky Linux:9 | All versions | 0:3.7.1-4.el9_8.2 |
oci-seccomp-bpf-hook Rocky Linux:9 | All versions | 0:1.2.11-2.el9_8 |
Products include Golang Go.
How do I fix CVE-2026-33811?
Upgrade golang to a fixed version for your release line: 1.25.10 or 1.26.3.
Upgrade to the fixed version. Memory-safe languages, compiler hardening and fuzzing prevent most new cases. More about Memory corruption.
Is CVE-2026-33811 being exploited?
There is no known exploitation of CVE-2026-33811 in the wild and no public exploit code.
Other vulnerabilities in Golang Go
- CVE-2020-0601 Microsoft Windows CryptoAPI Spoofing
- CVE-2026-27143 Missing bound checks can lead to memory corruption in safe Go in cmd/compile
- CVE-2024-24790 Unexpected behavior from Is methods for IPv4-mapped IPv6 addresses in net/netip
- CVE-2023-39320 Arbitrary code execution via go.mod toolchain directive in cmd/go
- CVE-2023-24540 Improper handling of JavaScript whitespace in html/template
Sources
Also known as ALSA-2026:36617, ALSA-2026:39266, ALSA-2026:39272, ALSA-2026:39319, AZL-98853, BELL-CVE-2026-33811 and 820 more.