CVE-2021-21703 (GCVE-0-2021-21703)

Vulnerability from cvelistv5 – Published: 2021-10-25 05:40 – Updated: 2024-09-17 03:02
VLAI
Title
PHP-FPM memory access in root process leading to privilege escalation
Summary
In PHP versions 7.3.x up to and including 7.3.31, 7.4.x below 7.4.25 and 8.0.x below 8.0.12, when running PHP FPM SAPI with main FPM daemon process running as root and child worker processes running as lower-privileged users, it is possible for the child processes to access memory shared with the main process and write to it, modifying it in a way that would cause the root process to conduct invalid memory reads and writes, which can be used to escalate privileges from local unprivileged user to the root user.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H
CWE
Assigner
php
References
Impacted products
Vendor Product Version
PHP Group PHP Affected: 7.3.x , ≤ 7.3.31 (custom)
Affected: 7.4.x , < 7.4.25 (custom)
Affected: 8.0.X , < 8.0.12 (custom)
Create a notification for this product.
Date Public
2021-10-18 00:00
Credits
Reported by Charles Fol
Show details on NVD website
To clipboard 

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demonio FPM principal ejecutado como root y los procesos worker hijos ejecutados como usuarios menos privilegiados, es posible que los procesos hijos accedan a la memoria compartida con el proceso principal y escriban en ella, modific\u00e1ndola de forma que causar\u00eda que el proceso root realizara lecturas y escrituras de memoria no v\u00e1lidas, que puede ser usado para escalar los privilegios del usuario local sin privilegios al usuario root\"}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"security@php.net\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:H\",\"baseScore\":7.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"CHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.1,\"impactScore\":6.0},{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":7.0,\"baseSeverity\":\"HIGH\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"HIGH\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.0,\"impactScore\":5.9}],\"cvssMetricV2\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"2.0\",\"vectorString\":\"AV:L/AC:M/Au:N/C:C/I:C/A:C\",\"baseScore\":6.9,\"accessVector\":\"LOCAL\",\"accessComplexity\":\"MEDIUM\",\"authentication\":\"NONE\",\"confidentialityImpact\":\"COMPLETE\",\"integrityImpact\":\"COMPLETE\",\"availabilityImpact\":\"COMPLETE\"},\"baseSeverity\":\"MEDIUM\",\"exploitabilityScore\":3.4,\"impactScore\":10.0,\"acInsufInfo\":false,\"obtainAllPrivilege\":false,\"obtainUserPrivilege\":false,\"obtainOtherPrivilege\":false,\"userInteractionRequired\":false}]},\"weaknesses\":[{\"source\":\"security@php.net\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-284\"},{\"lang\":\"en\",\"value\":\"CWE-787\"}]},{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-787\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:php:php:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"7.3.0\",\"versionEndIncluding\":\"7.3.31\",\"matchCriteriaId\":\"7FFE0A10-A39D-4BFA-A081-AA87CDCB56BB\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:php:php:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"7.4.0\",\"versionEndExcluding\":\"7.4.25\",\"matchCriteriaId\":\"E775E547-4990-4809-BE21-7E9B99059F1C\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:php:php:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"8.0.0\",\"versionEndExcluding\":\"8.0.12\",\"matchCriteriaId\":\"5633A8ED-60EF-4F14-A120-82A36BBD55A8\"}]}]},{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"DEECE5FC-CACF-4496-A3E7-164736409252\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"07B237A9-69A3-4A9C-9DA0-4E06BD37AE73\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:debian:debian_linux:11.0:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"FA6FEEC2-9F11-4643-8827-749718254FED\"}]}]},{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"E460AA51-FCDA-46B9-AE97-E6676AA5E194\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"A930E247-0B43-43CB-98FF-6CE7B8189835\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:fedoraproject:fedora:35:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"80E516C0-98A4-4ADE-B69F-66A772E2BAAA\"}]}]},{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:netapp:clustered_data_ontap:-:*:*:*:*:*:*:*\",\"matchCriteriaId\":\"1FE996B1-6951-4F85-AA58-B99A379D2163\"}]}]},{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:a:oracle:communications_diameter_signaling_router:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"8.0.0.0\",\"versionEndIncluding\":\"8.5.0.2\",\"matchCriteriaId\":\"590ADE5F-0D0F-4576-8BA6-828758823442\"}]}]}],\"references\":[{\"url\":\"http://www.openwall.com/lists/oss-security/2021/10/26/7\",\"source\":\"security@php.net\",\"tags\":[\"Mailing List\",\"Patch\",\"Third Party Advisory\"]},{\"url\":\"https://bugs.php.net/bug.php?id=81026\",\"source\":\"security@php.net\",\"tags\":[\"Exploit\",\"Issue Tracking\",\"Patch\",\"Vendor Advisory\"]},{\"url\":\"https://lists.debian.org/debian-lts-announce/2021/10/msg00021.html\",\"source\":\"security@php.net\",\"tags\":[\"Mailing List\",\"Third Party 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Advisory\"]},{\"url\":\"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/6PZVLICZUJMXOGWOUWSBAEGIVTF6Y6V3/\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\"},{\"url\":\"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/JO5RA6YOBGGGKLIA6F6BQRZDDECF5L3R/\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\"},{\"url\":\"https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/PBM3KKB3RY2YPOKNMC4HIH7IH3T3WC74/\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\"},{\"url\":\"https://security.gentoo.org/glsa/202209-20\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Third Party Advisory\"]},{\"url\":\"https://security.netapp.com/advisory/ntap-20211118-0003/\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Third Party Advisory\"]},{\"url\":\"https://www.debian.org/security/2021/dsa-4992\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Third Party Advisory\"]},{\"url\":\"https://www.debian.org/security/2021/dsa-4993\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Third Party Advisory\"]},{\"url\":\"https://www.oracle.com/security-alerts/cpuapr2022.html\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Patch\",\"Vendor Advisory\"]},{\"url\":\"https://www.oracle.com/security-alerts/cpujan2022.html\",\"source\":\"af854a3a-2127-422b-91ae-364da2661108\",\"tags\":[\"Patch\",\"Vendor Advisory\"]}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-06-28T07:43:21+00:00",
      "cve": "CVE-2021-21703",
      "id": "CVE-2021-21703",
      "initial_release_date": "2021-10-20T00:00:00+00:00",
      "product_status:fixed": "423",
      "product_status:known_affected": "101",
      "product_status:known_not_affected": "26",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "php: Local privilege escalation via PHP-FPM",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2021/cve-2021-21703.json",
      "version": "3"
    }
  }
}



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Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.