CVE-2019-18801
An untrusted remote client may send HTTP/2 requests that write to the heap outside of the request buffers when the upstream is HTTP/1.
Does this matter?
High impact if exploited, but EPSS currently rates exploitation as unlikely (2.50%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit.
Description
An issue was discovered in Envoy 1.12.0. An untrusted remote client may send HTTP/2 requests that write to the heap outside of the request buffers when the upstream is HTTP/1. This may be used to corrupt nearby heap contents (leading to a query-of-death scenario) or may be used to bypass Envoy's access control mechanisms such as path based routing. An attacker can also modify requests from other users that happen to be proximal temporally and spatially.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 2.50% probability · 85th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-787
- Affected
- envoyproxy/envoy
- Source
- cve@mitre.org
EPSS 2.5% since 26 October 2026; no change recorded yet. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- https://access.redhat.com/errata/RHSA-2019:4222Third Party Advisory
- https://blog.envoyproxy.ioProduct
- https://github.com/envoyproxy/envoy/commits/masterPatch
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-gxvv-x4p2-rpppExploit, Third Party Advisory
- https://groups.google.com/forum/#%21forum/envoy-users
- https://access.redhat.com/errata/RHSA-2019:4222Third Party Advisory
- https://blog.envoyproxy.ioProduct
- https://github.com/envoyproxy/envoy/commits/masterPatch
- https://github.com/envoyproxy/envoy/security/advisories/GHSA-gxvv-x4p2-rpppExploit, Third Party Advisory
- https://groups.google.com/forum/#%21forum/envoy-users
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.