CVE-2026-81856 (GCVE-0-2026-81856)
Vulnerability from cvelistv5
Published
2026-10-12 15:46
Modified
2026-10-16 17:47
CWE
  • CWE-150 - Improper Neutralization of Escape, Meta, or Control Sequences
Summary
Improper Neutralization of Escape, Meta, or Control Sequences vulnerability in hexpm hex allows a malicious package publisher or a hostile repository server to inject terminal control sequences into the output of Mix tasks. Hex prints strings supplied by the package repository and the documentation search service straight to the terminal through Hex.Shell.info/1 and Hex.Shell.error/1, neutralizing no control characters. Affected sinks span package metadata and configuration snippets in mix hex.info, search results in mix hex.package search and mix hex.search, owner and organization listings, publish and sponsor URLs, the authenticated username in mix hex.user, policy identities in mix hex.policy, and API error bodies rendered by Hex.Utils.print_error_result/1. A malicious package can embed ANSI escape sequences (cursor movement, line erase, carriage returns, OSC 52 clipboard writes) or Unicode bidirectional overrides in any of those fields, so the bytes reach the terminal unchanged, forging displayed URLs, package descriptions and suggested commands, concealing real output, or writing to the clipboard. No authentication or privileged position is required; only publishing a package. This issue affects hex: from 0.0.1 before 2.5.2.
Impacted products
Vendor Product Version
hexpm hex Version: 0.0.1   ≤
    cpe:2.3:a:hexpm:hex:*:*:*:*:*:*:*:*
Create a notification for this product.
   hexpm hex Version: 211303e3f68f5d3ce06450c1ff1a7a770a9ab236
    cpe:2.3:a:hexpm:hex:*:*:*:*:*:*:*:*
Create a notification for this product.
Show details on NVD website


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              "value": "\u003cp\u003eImproper Neutralization of Escape, Meta, or Control Sequences vulnerability in hexpm hex allows a malicious package publisher or a hostile repository server to inject terminal control sequences into the output of Mix tasks.\u003c/p\u003e\n\u003cp\u003eHex prints strings supplied by the package repository and the documentation search service straight to the terminal through \u003ccode\u003eHex.Shell.info/1\u003c/code\u003e and \u003ccode\u003eHex.Shell.error/1\u003c/code\u003e, neutralizing no control characters. Affected sinks span package metadata and configuration snippets in \u003ccode\u003emix hex.info\u003c/code\u003e, search results in \u003ccode\u003emix hex.package search\u003c/code\u003e and \u003ccode\u003emix hex.search\u003c/code\u003e, owner and organization listings, publish and sponsor URLs, the authenticated username in \u003ccode\u003emix hex.user\u003c/code\u003e, policy identities in \u003ccode\u003emix hex.policy\u003c/code\u003e, and API error bodies rendered by \u003ccode\u003eHex.Utils.print_error_result/1\u003c/code\u003e. A malicious package can embed ANSI escape sequences (cursor movement, line erase, carriage returns, OSC 52 clipboard writes) or Unicode bidirectional overrides in any of those fields, so the bytes reach the terminal unchanged, forging displayed URLs, package descriptions and suggested commands, concealing real output, or writing to the clipboard. No authentication or privileged position is required; only publishing a package.\u003c/p\u003e\n\u003cp\u003eThis issue affects hex: from 0.0.1 before 2.5.2.\u003c/p\u003e"
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              "value": "Improper Neutralization of Escape, Meta, or Control Sequences vulnerability in hexpm hex allows a malicious package publisher or a hostile repository server to inject terminal control sequences into the output of Mix tasks.\n\nHex prints strings supplied by the package repository and the documentation search service straight to the terminal through `Hex.Shell.info/1` and `Hex.Shell.error/1`, neutralizing no control characters. Affected sinks span package metadata and configuration snippets in `mix hex.info`, search results in `mix hex.package search` and `mix hex.search`, owner and organization listings, publish and sponsor URLs, the authenticated username in `mix hex.user`, policy identities in `mix hex.policy`, and API error bodies rendered by `Hex.Utils.print_error_result/1`. A malicious package can embed ANSI escape sequences (cursor movement, line erase, carriage returns, OSC 52 clipboard writes) or Unicode bidirectional overrides in any of those fields, so the bytes reach the terminal unchanged, forging displayed URLs, package descriptions and suggested commands, concealing real output, or writing to the clipboard. No authentication or privileged position is required; only publishing a package.\n\nThis issue affects hex: from 0.0.1 before 2.5.2."
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              "value": "Upgrade Hex to 2.5.2 or later, for example with `mix local.hex`. Hex then escapes terminal control characters in text from hex.pm and the registry before printing it, and rejects registry dependencies whose package or repository name isn\u0027t a valid name."
            }
          ],
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      "source": {
        "discovery": "EXTERNAL"
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      "title": "Terminal escape sequence injection in Hex via unneutralized server-supplied output"
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    "datePublished": "2026-10-12T15:46:12.146Z",
    "dateReserved": "2026-08-31T00:45:02.431Z",
    "dateUpdated": "2026-10-16T17:47:15.339Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
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Any developer who runs a documentation search that surfaces the attacker\u0027s package is affected.\", \"base64\": false}]}]}], \"metrics\": [{\"format\": \"CVSS\", \"cvssV4_0\": {\"Safety\": \"NOT_DEFINED\", \"version\": \"4.0\", \"Recovery\": \"NOT_DEFINED\", \"baseScore\": 2.3, \"Automatable\": \"NOT_DEFINED\", \"attackVector\": \"NETWORK\", \"baseSeverity\": \"LOW\", \"valueDensity\": \"NOT_DEFINED\", \"vectorString\": \"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N\", \"providerUrgency\": \"NOT_DEFINED\", \"userInteraction\": \"PASSIVE\", \"attackComplexity\": \"LOW\", \"attackRequirements\": \"PRESENT\", \"privilegesRequired\": \"NONE\", \"subIntegrityImpact\": \"NONE\", \"vulnIntegrityImpact\": \"LOW\", \"subAvailabilityImpact\": \"NONE\", \"vulnAvailabilityImpact\": \"NONE\", \"subConfidentialityImpact\": \"NONE\", \"vulnConfidentialityImpact\": \"NONE\", \"vulnerabilityResponseEffort\": \"NOT_DEFINED\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"GENERAL\"}]}], \"affected\": [{\"cpes\": [\"cpe:2.3:a:hexpm:hex:*:*:*:*:*:*:*:*\"], \"repo\": \"https://github.com/hexpm/hex\", \"vendor\": \"hexpm\", \"modules\": [\"\u0027Elixir.Mix.Tasks.Hex.Search\u0027\"], \"product\": \"hex\", \"versions\": [{\"status\": \"affected\", \"version\": \"0.0.1\", \"lessThan\": \"2.5.2\", \"versionType\": \"semver\"}], \"packageURL\": \"pkg:otp/hex?repository_url=https:%2F%2Fgithub.com%2Fhexpm%2Fhex\u0026vcs_url=repository_url=git%2Bhttps:%2F%2Fgithub.com%2Fhexpm%2Fhex.git\", \"packageName\": \"hex\", \"programFiles\": [\"lib/mix/tasks/hex.search.ex\"], \"defaultStatus\": \"unaffected\", \"programRoutines\": [{\"name\": \"\u0027Elixir.Mix.Tasks.Hex.Search\u0027:run/1\"}]}, {\"cpes\": [\"cpe:2.3:a:hexpm:hex:*:*:*:*:*:*:*:*\"], \"repo\": \"https://github.com/hexpm/hex\", \"vendor\": \"hexpm\", \"modules\": [\"\u0027Elixir.Mix.Tasks.Hex.Search\u0027\"], \"product\": \"hex\", \"versions\": [{\"status\": \"affected\", \"version\": \"211303e3f68f5d3ce06450c1ff1a7a770a9ab236\", \"lessThan\": \"dd3305ddf0032f6d0b468fd40dbbc3072bfcb8b8\", \"versionType\": \"git\"}], \"packageURL\": \"pkg:github/hexpm/hex\", \"packageName\": \"hexpm/hex\", \"programFiles\": [\"lib/mix/tasks/hex.search.ex\"], \"collectionURL\": \"https://github.com\", \"defaultStatus\": \"unaffected\", \"programRoutines\": [{\"name\": \"\u0027Elixir.Mix.Tasks.Hex.Search\u0027:run/1\"}]}], \"solutions\": [{\"lang\": \"en\", \"value\": \"Upgrade Hex to 2.5.2 or later, for example with mix local.hex. 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Hex then escapes terminal control characters in text from hex.pm and the registry before printing it, and rejects registry dependencies whose package or repository name isn\u0027t a valid name.\", \"base64\": false}]}], \"references\": [{\"url\": \"https://github.com/hexpm/hex/security/advisories/GHSA-fpmj-3cxg-p766\", \"name\": \"GitHub Advisory\", \"tags\": [\"related\", \"vendor-advisory\"]}, {\"url\": \"https://cna.erlef.org/cves/CVE-2026-81856.html\", \"name\": \"EEF CNA record for CVE-2026-81856\", \"tags\": [\"related\"]}, {\"url\": \"https://osv.dev/vulnerability/EEF-CVE-2026-81856\", \"name\": \"OSV record EEF-CVE-2026-81856\", \"tags\": [\"related\"]}, {\"url\": \"https://github.com/hexpm/hex/commit/211303e3f68f5d3ce06450c1ff1a7a770a9ab236\", \"name\": \"Introducing commit 211303e in hexpm/hex\", \"tags\": [\"related\"]}, {\"url\": \"https://github.com/hexpm/hex/commit/dd3305ddf0032f6d0b468fd40dbbc3072bfcb8b8\", \"name\": \"Fix commit dd3305d in hexpm/hex\", \"tags\": [\"patch\"]}], \"dateAssigned\": \"2026-09-09T16:47:17.000Z\", \"descriptions\": [{\"lang\": \"en\", \"value\": \"Improper Neutralization of Escape, Meta, or Control Sequences vulnerability in hexpm hex allows a malicious package publisher or a hostile repository server to inject terminal control sequences into the output of Mix tasks.\\n\\nHex prints strings supplied by the package repository and the documentation search service straight to the terminal through Hex.Shell.info/1 and Hex.Shell.error/1, neutralizing no control characters. Affected sinks span package metadata and configuration snippets in mix hex.info, search results in mix hex.package search and mix hex.search, owner and organization listings, publish and sponsor URLs, the authenticated username in mix hex.user, policy identities in mix hex.policy, and API error bodies rendered by Hex.Utils.print_error_result/1. A malicious package can embed ANSI escape sequences (cursor movement, line erase, carriage returns, OSC 52 clipboard writes) or Unicode bidirectional overrides in any of those fields, so the bytes reach the terminal unchanged, forging displayed URLs, package descriptions and suggested commands, concealing real output, or writing to the clipboard. No authentication or privileged position is required; only publishing a package.\\n\\nThis issue affects hex: from 0.0.1 before 2.5.2.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eImproper Neutralization of Escape, Meta, or Control Sequences vulnerability in hexpm hex allows a malicious package publisher or a hostile repository server to inject terminal control sequences into the output of Mix tasks.\u003c/p\u003e\\n\u003cp\u003eHex prints strings supplied by the package repository and the documentation search service straight to the terminal through \u003ccode\u003eHex.Shell.info/1\u003c/code\u003e and \u003ccode\u003eHex.Shell.error/1\u003c/code\u003e, neutralizing no control characters. Affected sinks span package metadata and configuration snippets in \u003ccode\u003emix hex.info\u003c/code\u003e, search results in \u003ccode\u003emix hex.package search\u003c/code\u003e and \u003ccode\u003emix hex.search\u003c/code\u003e, owner and organization listings, publish and sponsor URLs, the authenticated username in \u003ccode\u003emix hex.user\u003c/code\u003e, policy identities in \u003ccode\u003emix hex.policy\u003c/code\u003e, and API error bodies rendered by \u003ccode\u003eHex.Utils.print_error_result/1\u003c/code\u003e. A malicious package can embed ANSI escape sequences (cursor movement, line erase, carriage returns, OSC 52 clipboard writes) or Unicode bidirectional overrides in any of those fields, so the bytes reach the terminal unchanged, forging displayed URLs, package descriptions and suggested commands, concealing real output, or writing to the clipboard. No authentication or privileged position is required; only publishing a package.\u003c/p\u003e\\n\u003cp\u003eThis issue affects hex: from 0.0.1 before 2.5.2.\u003c/p\u003e\", \"base64\": false}, {\"type\": \"text/markdown\", \"value\": \"Improper Neutralization of Escape, Meta, or Control Sequences vulnerability in hexpm hex allows a malicious package publisher or a hostile repository server to inject terminal control sequences into the output of Mix tasks.\\n\\nHex prints strings supplied by the package repository and the documentation search service straight to the terminal through `Hex.Shell.info/1` and `Hex.Shell.error/1`, neutralizing no control characters. Affected sinks span package metadata and configuration snippets in `mix hex.info`, search results in `mix hex.package search` and `mix hex.search`, owner and organization listings, publish and sponsor URLs, the authenticated username in `mix hex.user`, policy identities in `mix hex.policy`, and API error bodies rendered by `Hex.Utils.print_error_result/1`. A malicious package can embed ANSI escape sequences (cursor movement, line erase, carriage returns, OSC 52 clipboard writes) or Unicode bidirectional overrides in any of those fields, so the bytes reach the terminal unchanged, forging displayed URLs, package descriptions and suggested commands, concealing real output, or writing to the clipboard. No authentication or privileged position is required; only publishing a package.\\n\\nThis issue affects hex: from 0.0.1 before 2.5.2.\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-150\", \"description\": \"CWE-150 Improper Neutralization of Escape, Meta, or Control Sequences\"}]}], \"configurations\": [{\"lang\": \"en\", \"value\": \"Reachable only when a developer runs an affected Mix task in a terminal emulator that interprets ANSI escape sequences, and the printed content originates from an attacker-published package or a hostile repository server.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eReachable only when a developer runs an affected Mix task in a terminal emulator that interprets ANSI escape sequences, and the printed content originates from an attacker-published package or a hostile repository server.\u003c/p\u003e\", \"base64\": false}, {\"type\": \"text/markdown\", \"value\": \"Reachable only when a developer runs an affected Mix task in a terminal emulator that interprets ANSI escape sequences, and the printed content originates from an attacker-published package or a hostile repository server.\", \"base64\": false}]}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:a:hexpm:hex:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"2.5.2\", \"versionStartIncluding\": \"0.0.1\"}], \"operator\": \"OR\"}], \"operator\": \"AND\"}], \"providerMetadata\": {\"orgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"shortName\": \"EEF\", \"dateUpdated\": \"2026-10-12T15:46:12.146Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-81856\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-10-16T17:47:15.339Z\", \"dateReserved\": \"2026-08-31T00:45:02.431Z\", \"assignerOrgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"datePublished\": \"2026-10-12T15:46:12.146Z\", \"assignerShortName\": \"EEF\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}


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Sightings

Author Source Type Date

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.


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