Heap Exhaustion via Unvalidated Len in Prometheus Remote Read (<3.5.3/3.11.3)
CVE-2026-42154 Published on May 4, 2026
Prometheus: remote read endpoint allows denial of service via crafted snappy payload
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.
Vulnerability Analysis
CVE-2026-42154 is exploitable with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have no impact on confidentiality and integrity, and a high impact on availability.
Weakness Types
What is a Resource Exhaustion Vulnerability?
The software does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.
CVE-2026-42154 has been classified to as a Resource Exhaustion vulnerability or weakness.
What is a Stack Exhaustion Vulnerability?
The product allocates memory based on an untrusted, large size value, but it does not ensure that the size is within expected limits, allowing arbitrary amounts of memory to be allocated.
CVE-2026-42154 has been classified to as a Stack Exhaustion vulnerability or weakness.
Products Associated with CVE-2026-42154
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Affected Versions
prometheus:- Version < 3.5.3 is affected.
- Version >= 3.6.0, < 3.11.3 is affected.