CVE-2021-37136 Bzip2Decoder doesn't allow setting size restrictions for decompressed data
Attackers can cause a denial of service via OutOfMemoryError in Netty's Bzip2 decoder by providing malicious input without size restrictions.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2021-37136?
CVE-2021-37136 is a high-severity denial of service vulnerability in Debian Debian Linux, published on 19 Oct 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
The Bzip2 decompression decoder function doesn't allow setting size restrictions on the decompressed output data (which affects the allocation size used during decompression). All users of Bzip2Decoder are affected. The malicious input can trigger an OOME and so a DoS attack
Weakness: CWE-400
Which versions are affected by CVE-2021-37136?
6 open source packages ship an affected version, including io.netty:netty, io.netty:netty-codec and org.jboss.netty:netty. It affects 19 products.
| Package | Affected | Fixed in |
|---|---|---|
io.netty:netty Maven | All versions | None |
io.netty:netty Maven | All versions | None |
io.netty:netty-codec Maven | All versions | 4.1.68.Final |
io.netty:netty-codec Maven | All versions | 4.1.68.Final |
org.jboss.netty:netty Maven | All versions | None |
org.jboss.netty:netty Maven | All versions | None |
Products include Debian Debian Linux, Netapp Oncommand Insight, Netty Netty, Oracle Banking Apis, Oracle Banking Digital Experience, Oracle Coherence and 13 more.
How do I fix CVE-2021-37136?
Upgrade to a fixed version.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-37136 being exploited?
There is no known exploitation of CVE-2021-37136 in the wild and no public exploit code.
Other vulnerabilities in Debian Debian Linux
Sources
Also known as CLEANSTART-2026-AS77854, CLEANSTART-2026-MT03413, CLSA-2025-1756771562, DEBIAN-CVE-2021-37136, GHSA-grg4-wf29-r9vv, MINI-364f-wpwc-r47v and 2 more.