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MEDIUM severity

CVE-2025-43915 — linkerd2

MEDIUM

CVE-2025-43915 is a medium-severity (CVSS 6.5) Uncontrolled Resource Consumption vulnerability in github.com/linkerd/linkerd2. A fix is available for github.com/linkerd/linkerd2 — see the affected versions and patch details below.

Linkerd resource exhaustion vulnerability

Also known asGHSA-42mr-jpwh-m9rvGO-2025-3664
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2025-43915.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk+0.01%
Lower risk than most CVEs27th percentile — riskier than 27% of all scored CVEsHighest risk
0.00%0.28%0.56%0.85%0.3%0.3%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
🐹github.com/linkerd/linkerd2

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

Description

In Linkerd edge releases before edge-25.2.1, and Buoyant Enterprise for Linkerd releases 2.13.0–2.13.7, 2.14.0–2.14.10, 2.15.0–2.15.7, 2.16.0–2.16.4, and 2.17.0–2.17.1, resource exhaustion can occur for Linkerd proxy metrics.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/linkerd/linkerd2all versions0.0.0-20250212165942-faa3f617eef5go get github.com/linkerd/linkerd2@v0.0.0-20250212165942-faa3f617eef5

Affected Products

2 products · 6 configurations
Application
buoyantlinkerd
≥ 2.17.0 && ≤ 2.15.7
range
Application
linkerdlinkerd
< 25.2.1
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 github.com/linkerd/linkerd2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update github.com/linkerd/linkerd2 to 0.0.0-20250212165942-faa3f617eef5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-43915 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

In Linkerd edge releases before edge-25.2.1, and Buoyant Enterprise for Linkerd releases 2.13.0–2.13.7, 2.14.0–2.14.10, 2.15.0–2.15.7, 2.16.0–2.16.4, and 2.17.0–2.17.1, resource exhaustion can occur for Linkerd proxy metrics.
O3 Security · Impact-Aware SCA

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CVE-2025-43915: linkerd2 DoS — Fix Available