CVE-2021-26722: Oncall Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-rfw2-x9f8-2f6m
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CVSS 6.1
CWE-79
Published
Advisory Summary

CVE-2021-26722 is a MODERATE (CVSS 6.1) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting Oncall libraries in the PyPI ecosystem. The issue involves linkedin oncall vulnerable to cross-site scripting. Remediation is available by upgrading affected packages to version 1.4.1.

CVE-2021-26722 at a Glance

CVE Identifier CVE-2021-26722
GHSA Identifier GHSA-rfw2-x9f8-2f6m
Severity MODERATE
CVSS v3.1 Base Score 6.1
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product Oncall
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 6.1

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Changed (S:C)
Confidentiality Low (C:L)
Integrity Low (I:L)
Availability None (A:N)

How to Fix CVE-2021-26722

To remediate this vulnerability, upgrade all affected Oncall dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

oncall fixed: 1.4.1 
pip install oncall>=1.4.1
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

pip show oncall

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2021-26722, inspect your installed packages using pip:

pip show oncall

Analyze the terminal output to locate any version of Oncall in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.4.1), your application is affected.

Note: The pip show oncall command checks currently installed packages in your active Python environment.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. In Oncall, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

LinkedIn Oncall through 1.4.0 allows reflected XSS via /query because of mishandling of the "No results found for" message in the search bar.

CVE-2021-26722 Affected Oncall Versions

1 component(s)
Fixed Versions:
1.4.1
Product / Package Ecosystem Affected Versions Fixed Version
oncall
pypi/oncall
PyPI
< 1.4.1
1.4.1

References

NVD — CVE-2021-26722 NVD
https://nvd.nist.gov/vuln/detail/CVE-2021-26722
Oncall Source Repository REPOSITORY
https://github.com/linkedin/oncall/issues/341
Security Fix Commit FIX COMMIT
https://github.com/linkedin/oncall/commit/843bc106a1c1b1699e9e52b6b0d01c7efe1d6225
GitHub Advisory / Wiki ADVISORY
https://github.com/advisories/GHSA-rfw2-x9f8-2f6m
Oncall Source Repository REPOSITORY
https://github.com/linkedin/oncall
Oncall Source Repository REPOSITORY
https://github.com/pypa/advisory-database/tree/main/vulns/oncall/PYSEC-2021-33.yaml
pypi.org/project/oncall WEB
https://pypi.org/project/oncall

Frequently Asked Questions

What is CVE-2021-26722?
CVE-2021-26722 is a security vulnerability in Oncall involving LinkedIn Oncall vulnerable to Cross-Site Scripting under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which Oncall versions are affected?
Affected versions include releases prior to 1.4.1 across affected packages: oncall.
What version fixes CVE-2021-26722?
Upgrading to 1.4.1 (or the latest patched release for your respective branch) resolves the vulnerability.
Is oncall affected?
Yes, oncall is affected in releases prior to 1.4.1. Upgrade your dependency to 1.4.1 or later.
What is the CVSS score of CVE-2021-26722?
CVE-2021-26722 has a CVSS v3.1 base score of 6.1 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2021-26722?
CVE-2021-26722 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check PyPI dependencies for CVE-2021-26722?
Run the dependency tree command: 'pip show oncall'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-rfw2-x9f8-2f6m",
  "modified" : "2024-10-07T21:22:52Z",
  "published" : "2021-04-30T17:27:53Z",
  "aliases" : [ "CVE-2021-26722" ],
  "summary" : "LinkedIn Oncall vulnerable to Cross-Site Scripting",
  "details" : "LinkedIn Oncall through 1.4.0 allows reflected XSS via /query because of mishandling of the \"No results found for\" message in the search bar.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
  }, {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:N/SC:L/SI:L/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "oncall"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.4.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2021-26722"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/linkedin/oncall/issues/341"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/linkedin/oncall/commit/843bc106a1c1b1699e9e52b6b0d01c7efe1d6225"
  }, {
    "type" : "ADVISORY",
    "url" : "https://github.com/advisories/GHSA-rfw2-x9f8-2f6m"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/linkedin/oncall"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/pypa/advisory-database/tree/main/vulns/oncall/PYSEC-2021-33.yaml"
  }, {
    "type" : "WEB",
    "url" : "https://pypi.org/project/oncall"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2021-04-28T19:21:42Z",
    "nvd_published_at" : "2021-02-05T18:15:00Z"
  }
}