NVD / CVE Program· CNA mitre

CVE-2019-15226: Upon receiving each incoming request header data, Envoy will iterate over existing request headers to verify that the total size of the head

Noroxi assessment

Priority: Plan (action score 49/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 64.5% (FIRST EPSS); higher than 99.2% of all records.
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
No fixed version is recorded, but the references include a patch (commit or PR) link.

Add it to your regular patch cycle. See the fix and affected versions sections below.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 7.5 · v3.1—No exploit No fix recorded

Published: Oct 9, 2019
Updated: Jun 16, 2026
EPSS: 64.5% · 99th percentile
CWE: CWE-400

Report tools

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Action score

Plan

Add it to your regular patch cycle.

CVSS: 30 / 40 · 7.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 19 / 30 · 64.5%

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Not in KEV: no record of exploitation in the wild
No public exploit code on record
No fixed version yet

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
envoyproxy	envoy	cpe:2.3:a:envoyproxy:envoy

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

envoyproxy envoy1.0.0
envoyproxy envoy1.1.0
envoyproxy envoy1.10.0
envoyproxy envoy1.11.0
envoyproxy envoy1.11.1
envoyproxy envoy1.11.2
envoyproxy envoy1.2.0
envoyproxy envoy1.3.0
envoyproxy envoy1.4.0
envoyproxy envoy1.5.0
envoyproxy envoy1.6.0
envoyproxy envoy1.7.0
envoyproxy envoy1.7.1
envoyproxy envoy1.8.0
envoyproxy envoy1.9.0
envoyproxy envoy1.9.1

Same product

envoyproxy: all records

Other highest-scoring records for the same primary product.

CVE-2024-30255HTTP/2: CPU exhaustion due to CONTINUATION frame flood
56Plan
CVE-2024-27919HTTP/2: memory exhaustion due to CONTINUATION frame flood
56Plan
CVE-2021-29492Bypass of path matching rules using escaped slash characters
52Plan

Published before and after this one in the same product

← EarlierCVE-2019-9901Apr 25, 2019 · Envoy 1.9.0 and before does not normalize HTTP URL paths.
41Plan
← EarlierCVE-2019-15225Aug 19, 2019 · In Envoy through 1.11.1, users may configure a route to match incoming path headers via the libstdc++ regular expression implementation.
31Monitor
Later →CVE-2019-18836Nov 10, 2019 · Envoy 1.12.0 allows a remote denial of service because of resource loops, as demonstrated by a single idle TCP connection being able to keep
31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

No fix version is recorded for this entry. Check the references for vendor advisories.

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: none
Integrity: none
Availability: high · the service can be disrupted

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: None
Integrity impact: None
Availability impact: High

Weakness class (CWE)

CWE-400 · Uncontrolled Resource Consumption

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-primary

Root cause

Code that parses nested structures sets no depth or size limit. A small input can turn into a disproportionate processing load.

The bug in code

The whole CWE-400 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1function expand(node) {
2  return node.children.map(expand);
3}

Fixed

1const MAX_DEPTH = 32;
2function expand(node, depth = 0) {
3  if (depth > MAX_DEPTH) throw new Error("too deep");
4  return node.children.map((c) => expand(c, depth + 1));
5}

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

Endpoint Denial of ServiceT1499

Change log

No changes recorded on tracked fields yet. Score, KEV, exploit maturity and fix status changes appear here.

References

github.com/envoyproxy/envoy/commit/afc39bea36fd436e54262f150c009e8d72db5014

Show all references (2 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records