HighCVE-2026-121808

    Memory exhaustion via compressed Erlang terms in the elixir-grpc Erlpack codec (CVE-2026-121808)

    Published Last modified Sources: CVE.org, EUVD, OSV

    Share

    What is affected, what to do

    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.

    Update Elixir-grpc Grpc to version 1.0.0, Elixir-grpc Grpc Core to version 1.1.0.

    Affected
    • Elixir-grpc Grpc lt 0.4.0..1.0.0
    • Elixir-grpc Grpc Core lt 1.0.0..1.1.0
    Fixed in
    • Elixir-grpc Grpc 1.0.0
    • Elixir-grpc Grpc Core 1.1.0

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    8.2

    XIEM Effective CVSS

    Highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v4

    8.2

    CVSS v4

    Severity High on the scale from 0 to 10.

    Source: CVE.org, EUVD, OSV

    —

    EPSS score

    No value is available for this vulnerability.

    Show all metrics
    Severity
    High
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    71.00 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    no public PoC known
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    8.2 Methodology
    CVSS v4

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    8.2
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    —
    Published
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-409

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    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.

    Source: cvelistv5, ENISA EUVD, NVD (NIST), CVE.org (MITRE), OSV (Open Source Vulnerabilities)

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    elixir-grpcgrpc
    • 0.4.0 – < 1.0.0
    • 1.0.0
    elixir-grpcgrpc_core
    • 1.0.0 – < 1.1.0
    • 1.1.0
    hexgrpc
    • 0.8.1
    • 0.11.1
    • 0.10.1
    • 0.7.0
    • 0.8.0
    • 0.5.0-beta.1
    • 0.10.2
    • 0.11.0
    • 0.9.0
    • 0.11.4
    • 0.11.2
    • 0.5.0
    • 0.4.0
    • 0.11.3
    • 0.11.5
    • 0.5.0-beta
    • 0.6.0
    • 1.0.0-rc.1
    • 0.10.0
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • —
    • 1.0.0
    • —
    • —
    • —
    • —
    • —
    • —
    hexgrpc_core
    • 1.0.4
    • 1.0.3
    • 1.0.1
    • 1.0.2
    • 1.0.5
    • 1.0.0
    • 1.0.6
    • —
    • —
    • —
    • —
    • —
    • 1.1.0
    • —

    Vendors and products

    Weakness classes (CWE)

    • CWE-409Improper Handling of Highly Compressed Data (Data Amplification)

      Base

      The product does not handle or incorrectly handles a compressed input with a very high compression ratio that produces a large output.

      Entry at MITRE CWE-409

    References & sources

    • github.comMemory exhaustion via compressed Erlang terms in the elixir-grpc Erlpack codecadvisory, Vendor advisory, related, euvd
    • cna.erlef.orgEEF CNA record for CVE-2026-121808web, related, euvd
    • github.comIntroducing commit 25bcc56 in elixir-grpc/grpcweb, related, euvd
    • github.comFix commit 0332faa in elixir-grpc/grpcfix, Patch, euvd
    • github.comFix commit d6bc56a in elixir-grpc/grpcfix, Patch, euvd
    • hex.pmpackages/grpcpackage
    • hex.pmpackages/grpc_corepackage
    • OSV (Open Source Vulnerabilities)OSV record EEF-CVE-2026-121808related, euvd

    Changes to this CVE

    Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

    1. ReceivedEEF

      CVSS V4.0: AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

      Weakness type: CWE-409

      Description added or changed

      Show 10 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      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.
      CVSSadded
      —
      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
      Weakness type (CWE)added
      —
      CWE-409
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/121xxx/CVE-2026-121808.json">CVE-2026-121808</a>
      Referenceadded
      —
      https://cna.erlef.org/cves/CVE-2026-121808.html
      Referenceadded
      —
      https://github.com/elixir-grpc/grpc/commit/0332faae5f5e132314794dbfdae5edecbccea292
      Referenceadded
      —
      https://github.com/elixir-grpc/grpc/commit/25bcc569fe2cc4478531a6c546c923205fc751c9
      Referenceadded
      —
      https://github.com/elixir-grpc/grpc/commit/d6bc56ac75dfb6c02db2099909210a37c9be8db6
      Referenceadded
      —
      https://github.com/elixir-grpc/grpc/security/advisories/GHSA-xxp9-7hp4-rqwp
      Referenceadded
      —
      https://osv.dev/vulnerability/EEF-CVE-2026-121808

      Source identifier: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

    Embed badge

    Show the severity and KEV status of this vulnerability on your site – with a link back here. The image is updated hourly.

    Badge preview for CVE-2026-121808
    <a href="https://intel.neosec.eu/en/cve/CVE-2026-121808"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-121808.svg?lang=en" alt="CVE-2026-121808 – NEOSEC Intel" height="20"></a>