How severe is CVE-2026-48853?

No CVSS score has been assigned to CVE-2026-48853 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-48853?

CVE-2026-48853 affects the following packages: grpc (Hex). Ecosystems affected: Hex.

How do I fix CVE-2026-48853?

Update grpc to 1.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-48853 is resolved across your whole dependency graph.

How do I detect CVE-2026-48853 in my Hex dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for grpc, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-48853 if there is no patch (or I can't update yet)?

Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Is CVE-2026-48853 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-48853 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-48853?

CVE-2026-48853 has an EPSS (Exploit Prediction Scoring System) score of 0.8%, placing it in the 55th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-48853?

CVE-2026-48853 is classified as Deserialization of Untrusted Data (CWE-502), CWE-770 (CWE-770). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-48853 published, and has it been updated?

CVE-2026-48853 was published on June 15, 2026 and was last updated on October 8, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

💧 Hex

Not in CISA KEV

CVE-2026-48853 — grpc

Fix: elixir-grpc/grpc@25bcc56

CVE-2026-48853 is a Deserialization of Untrusted Data vulnerability in grpc. A fix is available for grpc — see the affected versions and patch details below.

Remote code execution and denial of service via unsafe Erlang term deserialization in elixir-grpc/grpc

Also known asEEF-CVE-2026-48853GHSA-grp7-v8xh-rj7h

Published

Jun 15, 2026

Updated

Oct 8, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-48853.

EPSS Exploitation Probability

via FIRST.org ↗

0.8%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs55th percentile — riskier than 55% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

1 pkg affected

💧grpc

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Hex packages — download data is not available via public APIs for these ecosystems.

Description

Summary

GRPC.Codec.Erlpack.decode/2 calls :erlang.binary_to_term/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.binary_to_term(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.

2. RCE via fun materialization — Without :safe, binary_to_term/1 reconstructs fun and external-fun terms from wire data. If the decoded value reaches any call site that applies it (e.g. Enum.map, Task.async, direct invocation), attacker-controlled code executes inside the server process.

Configuration requirement: GRPC.Codec.Erlpack is not registered by default and must be explicitly added to the server's codecs option.

PoC

Start a gRPC server with codecs: [GRPC.Codec.Erlpack].
Open an HTTP/2 connection to the server.
Send a gRPC-framed POST to any RPC path with Content-Type: application/grpc+erlpack and a body of :erlang.term_to_binary(fn -> <malicious_code> end).
The server's decode/2 materializes the fun; any downstream call site that invokes the decoded value executes the attacker's code.
For DoS only: send payloads encoding fresh atoms in a loop until the atom table is exhausted and the VM crashes.

Impact

Affects grpc ≥ 0.4.0. Any server that explicitly registers GRPC.Codec.Erlpack is vulnerable to unauthenticated node-level DoS and potentially RCE.

References

Introduction commit: https://github.com/elixir-grpc/grpc/commit/25bcc569fe2cc4478531a6c546c923205fc751c9
Patch commit: https://github.com/elixir-grpc/grpc/commit/272a97a5ea1b46af1819f14a831fcf35fc91f992

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
💧Hex	`grpc`	≥ 0.4.0&&< 1.0.0	1.0.0`mix deps.update grpc`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for grpc, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update grpc to 1.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-48853 is resolved across your whole dependency graph.
Workarounds
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade.

Frequently Asked Questions

### Summary `GRPC.Codec.Erlpack.decode/2` calls `:erlang.binary_to_term/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.binary_to_term(binary)` call with no `:safe` flag, no size limit, and no typ

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