Eclipse Vert.x: request smuggling

Eclipse Foundation Eclipse Vert.x

Eclipse Vert.x HTTP/1.x decoder vulnerable to request smuggling, affecting vertx-core with around 2,100 Maven dependents and 300 million cumulative downloads

Do this now

Upgrade io.vertx:vertx-core to 5.2.1 or 5.1.10, and Eclipse Vert.x to 5.1.10.

Fix it

Eclipse Vert.x

On 5.xUpgrade to Eclipse Vert.x 5.1.10
On 5.xFix not named in the CVE record: see vendor advisory
On 5.xNo fix on 5.0.x yet

io.vertx:vertx-core maven

On 5.1.x?mvn versions:use-dep-version -Dincludes=io.vertx:vertx-core -DdepVersion=5.1.10 -DforceVersion=true
On 5.2.x?mvn versions:use-dep-version -Dincludes=io.vertx:vertx-core -DdepVersion=5.2.1 -DforceVersion=true

First seen: 28 Oct 2026
Last update: 28 Oct 2026, 18:19 UTC
Fixed in: io.vertx:vertx-core 5.2.1
io.vertx:vertx-core 5.1.10
Eclipse Vert.x 5.1.10
Identifiers: CVE-2026-102479
CVSS: 5.9
Source: news
On the menu as: Java

Check this repository for exposure to one security incident from pwned.coffee. Report first, change nothing until I say so.

## Eclipse Vert.x: request smuggling
Severity: medium. Patch status: partial fix.
Affected: Eclipse Foundation Eclipse Vert.x
Fixed in: io.vertx:vertx-core 5.2.1, io.vertx:vertx-core 5.1.10, Eclipse Vert.x 5.1.10
Ids: CVE-2026-102479

Eclipse Vert.x HTTP/1.x decoder vulnerable to request smuggling, affecting vertx-core with around 2,100 Maven dependents and 300 million cumulative downloads

## Steps
1. Search every lockfile and manifest (package-lock.json, yarn.lock, pnpm-lock.yaml, requirements*.txt, poetry.lock, uv.lock, composer.lock, go.sum, Cargo.lock, Gemfile.lock) for `io.vertx:vertx-core`. For each hit, compare the installed version with the fix on the same major line: io.vertx:vertx-core 5.2.1, io.vertx:vertx-core 5.1.10, Eclipse Vert.x 5.1.10. If it's lower, give the exact upgrade command for the package manager this repo uses.
2. Fix by release line: io.vertx:vertx-core: 5.2.0 → 5.2.1; >= 5.0.0 <= 5.1.8 → 5.1.10. Eclipse Vert.x: 5.1.x → 5.1.10; 5.0.x → no fix on 5.0.x yet. Eclipse Vert.x 5.2.x: the CVE record names no fix; check the vendor advisory before assuming there is none. Until one ships: restrict network access to it.

## Fix by release line
| Line | State | Fix | Until then |
|---|---|---|---|
| io.vertx:vertx-core 5.2.0 | fixed | 5.2.1 | — |
| io.vertx:vertx-core >= 5.0.0 <= 5.1.8 | fixed | 5.1.10 | — |
| Eclipse Vert.x 5.2.x | not named in the CVE record | check the vendor advisory: https://github.com/eclipse-vertx/vert.x/security/advisories/GHSA-ch7p-g5pm-3gqx | restrict network access to it |
| Eclipse Vert.x 5.1.x | fixed | 5.1.10 | — |
| Eclipse Vert.x 5.0.x | migrate | move to 5.1.10 | restrict network access to it |

## Report
A table: file, product or package, version in use, affected yes/no, exact fix. Then anything a human has to check outside the repo.

If you have the pwned.coffee MCP server (https://pwned.coffee/mcp), call lookup_cve("CVE-2026-102479") for the latest, and check_repo with this repo's lockfiles, Dockerfiles and workflows for a full receipt.
Sources: https://seclists.org/oss-sec/2026/q4/426
https://pwned.coffee/i/eclipse-vert-x-request-smuggling-cve-2026-102479

Timeline

28 Oct 2026, 18:19 UTC
Fix status: unknown → partial fix.
28 Oct 2026
First reported.

Receipt

Exploitation: No known exploitation
Fix by release line: Product Affected Fixed in Source
io.vertx:vertx-core (maven) 5.2.0 5.2.1 GitHub advisory checked 28 Oct
io.vertx:vertx-core (maven) >= 5.0.0, <= 5.1.8 5.1.10 GitHub advisory checked 28 Oct
Eclipse Vert.x = 5.2.0 fix not named in the CVE record: see vendor advisory CVE record (CNA) checked 28 Oct
Eclipse Vert.x 5.1.0 to before 5.1.10 5.1.10 NVD checked 28 Oct
Eclipse Vert.x <= 5.0.12 no fix on 5.0.x yet CVE record (CNA) checked 28 Oct
The CVE record names no fix for one line; the vendor’s advisory may: github.com
Score: CVSS 5.9 (medium). CVSS 3.1 5.9 (NVD) for CVE-2026-102479
Last checked: 28 Oct 2026, 18:19 UTC

Product	Affected	Fixed in	Source
io.vertx:vertx-core (maven)	5.2.0	5.2.1	GitHub advisory checked 28 Oct
io.vertx:vertx-core (maven)	>= 5.0.0, <= 5.1.8	5.1.10	GitHub advisory checked 28 Oct
Eclipse Vert.x	= 5.2.0	fix not named in the CVE record: see vendor advisory	CVE record (CNA) checked 28 Oct
Eclipse Vert.x	5.1.0 to before 5.1.10	5.1.10	NVD checked 28 Oct
Eclipse Vert.x	<= 5.0.12	no fix on 5.0.x yet	CVE record (CNA) checked 28 Oct

Sources: KEV – CVE record ✓ Vendor ✓

Sources

seclists.org: CVE-2026-102479: Request smuggling in Eclipse Vert.x HTTP/1.x decoder

Wrong fix version, or a source we missed? Send it back to chef@pwned.coffee with the source, and we'll correct it here.

Totalone coffee