CVE-2026-53954: Bugsink Denial of Service Vulnerability

MODERATE
Advisory Identifier: GHSA-5x67-j5xg-c5gj
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CVSS 4.3
CWE-400
Published
Advisory Summary

CVE-2026-53954 is a MODERATE (CVSS 4.3) denial of service vulnerability (CWE-400: Uncontrolled Resource Consumption) affecting Bugsink libraries in the PyPI ecosystem. The issue involves dos using large numbers of event tags. Remediation is available by upgrading affected packages to version 2.2.2.

CVE-2026-53954 at a Glance

CVE Identifier CVE-2026-53954
GHSA Identifier GHSA-5x67-j5xg-c5gj
Severity MODERATE
CVSS v3.1 Base Score 4.3
CWE Classification CWE-400: Uncontrolled Resource Consumption
Affected Product Bugsink
Package Ecosystem PyPI
Published Date
Last Updated

Security Impact

CVSS: 4.3

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

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

How to Fix CVE-2026-53954

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

bugsink fixed: 2.2.2 
pip install bugsink>=2.2.2
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 bugsink

How to Check if You Are Affected

To determine whether your Python environment is affected by CVE-2026-53954, inspect your installed packages using pip:

pip show bugsink

Analyze the terminal output to locate any version of Bugsink in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 2.2.2), your application is affected.

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

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-400: Uncontrolled Resource Consumption, where the product does not properly control the allocation and maintenance of a limited resource. In Bugsink, 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

### Summary In affected versions, Bugsink stores every tag supplied with an incoming event. An event with an unusually large number of custom (i.e. supplied by an attacker) tags can therefore make ingestion spend more time than intended writing tag rows. Bugsink uses a single-writer database architecture. That keeps the implementation simple, but it also means one expensive write transaction can delay other event digestion while it is running. In this case, it makes ingestion of other events wait until the transaction that writes the tags finishes, which effectively causes a temporary denial of service for other events. ### Impact Submitting such an event requires a valid project DSN. DSNs are sometimes visible in client-side applications, so they should not be treated as a strong security boundary, but the issue is still limited to ingestion for a Bugsink instance that accepts the event. The impact is availability-only. The issue does not expose stored data, modify existing events, or allow code execution. ### Mitigation Update to version 2.2.2, which caps the number of tags stored for a single event. The default cap is 100 tags and can be changed with `MAX_EVENT_TAGS`.

CVE-2026-53954 Affected Bugsink Versions

1 component(s)
Fixed Versions:
2.2.2
Product / Package Ecosystem Affected Versions Fixed Version
bugsink
pypi/bugsink
PyPI
< 2.2.2
2.2.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/bugsink/bugsink/security/advisories/GHSA-5x67-j5xg-c5gj
Bugsink Source Repository REPOSITORY
https://github.com/bugsink/bugsink
Bugsink Release RELEASE
https://github.com/bugsink/bugsink/releases/tag/2.2.2

Frequently Asked Questions

What is CVE-2026-53954?
CVE-2026-53954 is a security vulnerability in Bugsink involving DOS using large numbers of event tags under CWE-400: Uncontrolled Resource Consumption.
Which Bugsink versions are affected?
Affected versions include releases prior to 2.2.2 across affected packages: bugsink.
What version fixes CVE-2026-53954?
Upgrading to 2.2.2 (or the latest patched release for your respective branch) resolves the vulnerability.
Is bugsink affected?
Yes, bugsink is affected in releases prior to 2.2.2. Upgrade your dependency to 2.2.2 or later.
What is the CVSS score of CVE-2026-53954?
CVE-2026-53954 has a CVSS v3.1 base score of 4.3 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L.
What CWE is associated with CVE-2026-53954?
CVE-2026-53954 is classified under CWE-400: Uncontrolled Resource Consumption (The product does not properly control the allocation and maintenance of a limited resource.).
How can I check PyPI dependencies for CVE-2026-53954?
Run the dependency tree command: 'pip show bugsink'. 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-5x67-j5xg-c5gj",
  "modified" : "2026-06-12T19:24:20Z",
  "published" : "2026-06-05T21:45:40Z",
  "aliases" : [ "CVE-2026-53954" ],
  "summary" : "Bugsink: DOS using large numbers of event tags",
  "details" : "### Summary\n\nIn affected versions, Bugsink stores every tag supplied with an incoming event. An event with an unusually large number\nof custom (i.e. supplied by an attacker) tags can therefore make ingestion spend more time than intended writing tag rows.\n\nBugsink uses a single-writer database architecture. That keeps the implementation simple, but it also means one\nexpensive write transaction can delay other event digestion while it is running. In this case, it makes ingestion of\nother events wait until the transaction that writes the tags finishes, which effectively causes a temporary denial of\nservice for other events.\n\n### Impact\n\nSubmitting such an event requires a valid project DSN. DSNs are sometimes visible in client-side applications, so they\nshould not be treated as a strong security boundary, but the issue is still limited to ingestion for a Bugsink instance\nthat accepts the event.\n\nThe impact is availability-only. The issue does not expose stored data, modify existing events, or allow code execution.\n\n### Mitigation\n\nUpdate to version 2.2.2, which caps the number of tags stored for a single event. The default cap is 100 tags and can\nbe changed with `MAX_EVENT_TAGS`.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "PyPI",
      "name" : "bugsink"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.2.2"
      } ]
    } ],
    "database_specific" : {
      "last_known_affected_version_range" : "<= 2.2.1"
    }
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/bugsink/bugsink/security/advisories/GHSA-5x67-j5xg-c5gj"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/bugsink/bugsink"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/bugsink/bugsink/releases/tag/2.2.2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-400" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-05T21:45:40Z",
    "nvd_published_at" : null
  }
}