CVE-2026-42154 Prometheus: remote read endpoint allows denial of service via crafted snappy payload
Unauthenticated attackers can crash Prometheus by sending crafted snappy payloads to the remote read endpoint, causing memory exhaustion.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-42154?
CVE-2026-42154 is a high-severity denial of service vulnerability in prometheus, published on 4 May 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Prometheus is an open-source monitoring system and time series database. Prior to versions 3.5.3 and 3.11.3, the remote read endpoint (/api/v1/read) does not validate the declared decoded length in a snappy-compressed request body before allocating memory. An unauthenticated attacker can send a small payload that causes a huge heap allocation per request. Under concurrent load this can exhaust available memory and crash the Prometheus process. This issue has been patched in versions 3.5.3 and 3.11.3.
Which versions are affected by CVE-2026-42154?
9 open source packages ship an affected version, including github.com/prometheus/prometheus, prometheus and github.com/prometheus/prometheus/v2. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
github.com/prometheus/prometheus Go | All versions | 0.305.2, 0.311.3 |
github.com/prometheus/prometheus Go | All versions | 0.305.2 |
github.com/prometheus/prometheus Go | All versions | 0.305.2 |
github.com/prometheus/prometheus Go | From 0.306.0 | 0.311.3 |
github.com/prometheus/prometheus Go | From 0.306.0 | 0.311.3 |
github.com/prometheus/prometheus Go | From 1.0.0-rc.0 to 2.5.0 | None |
3 more packages
github.com/prometheus/prometheus Go | From 1.0.0-rc.0 to 2.5.0 | None |
prometheus Bitnami | All versions | 0.305.3, 0.311.3, 3.5.3, 3.11.3 |
github.com/prometheus/prometheus/v2 Go | All versions | None |
Products include Prometheus Prometheus.
How do I fix CVE-2026-42154?
Upgrade github.com/prometheus/prometheus to a fixed version for your release line: 0.305.2 or 0.311.3.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-42154 being exploited?
There is no known exploitation of CVE-2026-42154 in the wild and no public exploit code.
Public exploit code: 1 proofs of concept on GitHub.
Other vulnerabilities in prometheus
- CVE-2026-42151 Prometheus Azure AD remote write OAuth client secret exposed via config API
- CVE-2021-29622 Arbitrary redirects under /new endpoint
- CVE-2019-3826 Cross-site scripting in prometheus
- CVE-2026-40179 Prometheus: Stored XSS via metric names and label values in web UI tooltips and metrics explorer
- CVE-2026-44903 Prometheus: Stored XSS via crafted histogram bucket label values in the heatmap display of the old Prometheus web UI
Sources
Also known as AZL-86607, BIT-prometheus-2026-42154, CLEANSTART-2026-CA81083, CLEANSTART-2026-DF38360, CLEANSTART-2026-DV32508, CLEANSTART-2026-GD06163 and 161 more.