CVE-2026-121808
What it is
Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in elixir-grpc grpc_core and grpc allows unauthenticated attackers to exhaust server memory via a compressed Erlang external term in a gRPC message body. GRPC.Codec.Erlpack.decode/2 (grpc_core/lib/grpc/codec/erlpack.ex, and lib/grpc/codec/erlpack.ex before the package split) passes the message body to :erlang.binary_to_term/2. That function inflates a compressed term in full before it returns. The codec sets no limit on the decoded size, and its type checks run only on the decoded term. The server's max_body_size limit counts the compressed bytes of the request. A request with Content-Type: application/grpc+erlpack can therefore make the server allocate a term much larger than the request body. This issue affects grpc: from 0.4.0 before 1.0.0; grpc_core: from 1.0.0 before 1.1.0.
At a glance
- Exploitability
- Can be exploited over the network without logging in. High risk of service disruption.
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- ReservedThe CVE id was reserved by its CNA
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: not scored yet.
- Severity: 8.2 HIGH (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Weakness
- CWE-409
- Record status
- Received
Attack profile CVSS 4.0 · 8.2
- Attack vector
- Network
- Complexity
- Low
- Attack requirements
- Present
- Privileges needed
- None
- User interaction
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Raw vector
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-121808.md and follow it. Check whether this project is affected by CVE-2026-121808. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://github.com/elixir-grpc/grpc/commit/0332faae5f5e132314794dbfdae5edecbccea292
- https://github.com/elixir-grpc/grpc/commit/25bcc569fe2cc4478531a6c546c923205fc751c9
- https://github.com/elixir-grpc/grpc/commit/d6bc56ac75dfb6c02db2099909210a37c9be8db6
- https://github.com/elixir-grpc/grpc/security/advisories/GHSA-xxp9-7hp4-rqwp
References
- https://cna.erlef.org/cves/CVE-2026-121808.html
- https://github.com/elixir-grpc/grpc/commit/0332faae5f5e132314794dbfdae5edecbccea292
- https://github.com/elixir-grpc/grpc/commit/25bcc569fe2cc4478531a6c546c923205fc751c9
- https://github.com/elixir-grpc/grpc/commit/d6bc56ac75dfb6c02db2099909210a37c9be8db6
- https://github.com/elixir-grpc/grpc/security/advisories/GHSA-xxp9-7hp4-rqwp
- https://osv.dev/vulnerability/EEF-CVE-2026-121808