CVE-2026-48853: gRPC Erlang package vulnerable to Remote Code Execution with attacker-controlled gRPC payloads

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• Not in CISA KEV, but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
• EPSS 0.8%, percentile 56: FIRST’s model estimates a 0.8% chance of exploitation activity in the next 30 days, higher than 56% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes grpc (Hex (Erlang/Elixir)) >= 0.4.0, < 1.0.0, fixed in 1.0.0. Check your lockfile, including transitive dependencies.

What it is

Deserialization of Untrusted Data and Allocation of Resources Without Limits or Throttling vulnerabilities in elixir-grpc grpc allow unauthenticated attackers to crash the BEAM node via atom table exhaustion and, when a decoded term flows into a call site that invokes it, achieve remote code execution on the server. 'Elixir.GRPC.Codec.Erlpack':decode/2 (lib/grpc/codec/erlpack.ex) calls :erlang.binarytoterm/1 on the raw gRPC message body without the :safe option, no size bound, and no type guard. Any unauthenticated peer that sends a request with Content-Type: application/grpc+erlpack can send a crafted payload that mints arbitrary new atoms (which are never garbage-collected, exhausting the bounded atom table and crashing the VM) or that encodes a fun term which, if applied anywhere downstream, executes attacker-controlled code inside the server process. This issue affects grpc: from 0.4.0 before 1.0.0.

From the GitHub advisory

Summary

GRPC.Codec.Erlpack.decode/2 calls :erlang.binarytoterm/1 directly on the raw gRPC message body without the :safe option. Any unauthenticated peer that can reach a gRPC endpoint with Content-Type: application/grpc+erlpack can crash the entire BEAM node via atom table exhaustion or, if a decoded fun term flows into a call site that invokes it, achieve remote code execution inside the server process.

Details

Root cause — lib/grpc/codec/erlpack.ex implements decode/2 as a bare :erlang.binarytoterm(binary) call with no :safe flag, no size limit, and no type validation. This has two independent exploitation paths:

1. DoS via atom exhaustion — BEAM atoms are never garbage-collected and the global atom table is bounded (~1,048,576 entries). A crafted payload encoding large numbers of fresh atoms saturates the table and crashes the entire VM, taking down all applications on the node.

Weakness type: CWE-502, CWE-770.

Product: grpc (Hex (Erlang/Elixir)) · Assigned by: EEF · Published: 2026-06-15

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: present (depends on deployment conditions)
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation poc, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.78% probability of exploitation activity in the next 30 days; percentile 56.

Timeline

• 2026-06-15 — CVE record published by EEF
• 2026-08-25 — GitHub-reviewed advisory GHSA-grp7-v8xh-rj7h published (critical)
• 2026-09-24 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. github.com github.com
2. Fix commit 272a97a in elixir-grpc/grpc github.com

Vulnerability records

1. GitHub Advisory GHSA-grp7-v8xh-rj7h github.com
2. CVE.org record CVE-2026-48853 cve.org
3. NVD entry CVE-2026-48853 nvd.nist.gov

Other references from the CVE record and advisory

1. EEF CNA record for CVE-2026-48853 cna.erlef.org
2. OSV record EEF-CVE-2026-48853 osv.dev
3. Introducing commit 25bcc56 in elixir-grpc/grpc github.com
4. github.com github.com
5. github.com github.com

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