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💎 RubyGems
Not in CISA KEV
MEDIUM severity

CVE-2021-39880 — apollo_upload_server

MEDIUMFix: jetruby/apollo_upload_server-ruby#44

CVE-2021-39880 is a medium-severity (CVSS 6.5) vulnerability in apollo_upload_server. A fix is available for apollo_upload_server — see the affected versions and patch details below.

apollo_upload_server has Denial of Service vulnerability

Also known asBIT-gitlab-2021-39880GHSA-w6pv-c757-6rgr
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 8, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
2.1%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs82th percentile — riskier than 82% of all scored CVEsHighest risk
0.00%0.86%1.71%2.57%0.4%2.1%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
💎apollo_upload_server

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.

Description

A Denial Of Service vulnerability in the apollo_upload_server Ruby gem in GitLab CE/EE all versions starting from 11.9 before 14.0.9, all versions starting from 14.1 before 14.1.4, and all versions starting from 14.2 before 14.2.2 allows an attacker to deny access to all users via specially crafted requests to the apollo_upload_server middleware.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
💎RubyGemsapollo_upload_serverall versions2.1.0bundle update apollo_upload_server --conservative

Affected Products

1 product · 6 configurations
Application
gitlabgitlab
≥ 14.2.0 && < 14.2.2
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for apollo_upload_server, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update apollo_upload_server to 2.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-39880 is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

A Denial Of Service vulnerability in the apollo_upload_server Ruby gem in GitLab CE/EE all versions starting from 11.9 before 14.0.9, all versions starting from 14.1 before 14.1.4, and all versions starting from 14.2 before 14.2.2 allows an attacker to deny access to all users via specially crafted requests to the apollo_upload_server middleware.
O3 Security · Impact-Aware SCA

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CVE-2021-39880: apollo_upload DoS — Fixed in 2.1.0