Public proof of conceptFix available

CVE-2026-42154

Q: Is CVE-2026-42154 actively exploited?

Active exploitation of CVE-2026-42154 has not been confirmed. Its EPSS score was 0.8% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

Q: What is the CVSS score for CVE-2026-42154?

CVE-2026-42154 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

A public proof of concept exists; no exploitation attested.

Published2026-05-04
Fixed in3.11.3 · 3.5.3
WeaknessCWE-400 · CWE-770 · CWE-789

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC

2026-05-0419:16CVE publishedNVD

Observed activity

isMalicious corpus · updated 2026-10-23 18:48 UTC

Indicators tagged with this CVE, per day0 indicators over 7 days

Block these indicators

Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2026-42154?format=txt
CSV export: https://api.ismalicious.com/edl/cve/CVE-2026-42154?format=csv
TAXII collection of exploited CVEs
The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD · OSV

Prometheus

Branch	Affected	Fixed in	Source
3.x	≥ 3.6.0, < 3.11.3	3.11.3	NVD
3.5	< 3.5.3	3.5.3	NVD

prometheus

Branch	Affected	Fixed in	Source
0.305	< 0.305.3	0.305.3	OSV

prometheus/prometheus

Branch	Affected	Fixed in	Source
0.305	< 0.305.2	0.305.2	OSV

1 more product in the sources.

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

opentelemetry-collectorAlmaLinux:10all versions · fixed in 0.152.1-1.el10_2
opentelemetry-collectorAlmaLinux:9all versions · fixed in 0.152.1-1.el9_8

Vendor advisories

CVE-2026-42154 Red Hat Product Security310 products fixed · 38 known affected
github.com/prometheus/prometheus: Prometheus: Denial of Service via uncontrolled memory allocation in remote read endpoint
compliance/openshift-file-integrity-operator-bundle as a component of File Integrity Operator · openshift-lightspeed/openshift-mcp-server-rhel9 as a component of OpenShift Lightspeed · rhceph/rhceph-5-dashboard-rhel8 as a component of Red Hat Ceph Storage 5 · +35 more
RHSA-2026:83013 Red Hat Product Security4 products fixed
Red Hat Security Advisory: Logging for Red Hat OpenShift - 6.0.17
RHSA-2026:77639 Red Hat Product Security12 products fixed
Red Hat Security Advisory: Logging for Red Hat OpenShift - 6.4.7
RHSA-2026:74511 Red Hat Product Security4 products fixed
Red Hat Security Advisory: Red Hat Quay 3.17.5
RHSA-2026:70870 Red Hat Product Security4 products fixed
Red Hat Security Advisory: Logging for Red Hat OpenShift - 6.5.3
RHSA-2026:70267 Red Hat Product Security4 products fixed
Red Hat Security Advisory: Red Hat Quay 3.14.9

49 more advisories

Full record on NVD

Fix

Update Prometheus to 3.11.3 · 3.5.3
Vendor fix Red Hat Product Security RHSA-2026:83013 · 4 productsFor OpenShift Container Platform 4.16 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.16/html/relea…
Vendor fix Red Hat Product Security RHSA-2026:77639 · 12 productsFor OpenShift Container Platform 4.20 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.20/html/relea…
Vendor fix Red Hat Product Security RHSA-2026:74511 · 4 productsBefore applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11258
Vendor fix Red Hat Product Security RHSA-2026:70870 · 4 productsFor OpenShift Container Platform 4.21 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.21/html/relea…
Vendor fix Red Hat Product Security RHSA-2026:70267 · 4 productsBefore applying this update, make sure all previously released errata relevant to your system have been applied. For details on how to apply this update, refer to: https://access.redhat.com/articles/11458
Vendor fix Red Hat Product Security RHSA-2026:65840 · 1 productFor OpenShift Container Platform 4.13 see the following documentation, which will be updated shortly for this release, for important instructions on how to upgrade your cluster and fully apply this asynchronous errata update: https://docs.redhat.com/en/documentation/openshift_container_platform/4.…

Advisories and patches

github.comPatch
github.comPatch
github.comRelease Notes
github.comRelease Notes
github.comVendor Advisory

Detection

read 2026-10-23 19:25 UTC

Nuclei template: none so far
Exploit-DB: no entry
Proof-of-concept repositories: 1 repository, unverifiedShadowByte1/CVE-2026-42154

Sources

NVDCVE recordread 2026-10-23
CISA-ADPSSVC decisionnone2026-05-04
OpenCVESSVC decisionnone—
CNACVSS 3.17.5read 2026-10-23
CNAweakness (CWE)CWE-400, CWE-770, CWE-789read 2026-10-23
FIRST EPSSEPSS score0.8 %2026-10-22
PoC-in-GitHubproof of concept1read 2026-10-23
OSVaffected packages—
Microsoft MSRCadvisory—

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published: 2026-05-04
Last Modified: 2026-09-10
NVD status: Modified
MSRC Title: Prometheus: remote read endpoint allows denial of service via crafted snappy payload

Frequently asked questions

What is CVE-2026-42154?

Is CVE-2026-42154 actively exploited?

Active exploitation of CVE-2026-42154 has not been confirmed. Its EPSS score was 0.8% on 2026-10-22, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-42154?

CVE-2026-42154 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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