SOC status:Duty analyst on shift

UK Cyber Defence
VulnerabilityModified

CVE-2019-15226

A remote attacker may craft a request that stays below the maximum request header size but consists of many thousands of small headers to consume CPU and result in a denial-of-service attack.

HIGH 7.5EPSS 64.5%

Does this matter?

EPSS puts the probability of exploitation in the next 30 days at 64.5%, higher than 99% of all known CVEs. Patch or mitigate before the next change window.

Description

Upon receiving each incoming request header data, Envoy will iterate over existing request headers to verify that the total size of the headers stays below a maximum limit. The implementation in versions 1.10.0 through 1.11.1 for HTTP/1.x traffic and all versions of Envoy for HTTP/2 traffic had O(n^2) performance characteristics. A remote attacker may craft a request that stays below the maximum request header size but consists of many thousands of small headers to consume CPU and result in a denial-of-service attack.

CVSS 3.1
7.5 HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS
64.52% probability · 99th percentile
Public exploits
None in Exploit-DB
CISA KEV
Not listed
Weakness
CWE-400
Affected
envoyproxy/envoy
Source
cve@mitre.org
EPSS trend
0%33%65%27 October 2026: 64.52%27 October 202627 October 2026

EPSS 64.5% since 27 October 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.

References

Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.