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CVE-2021-3859

CVE-2021-3859: Undertow vulnerable to Denial of Service (DoS) attacks

7.5

CVSS Score
3.1

Basic Information

CVE ID
CVE-2021-3859
GHSA ID
GHSA-339q-62wm-c39w
EPSS Score
0.41546%
CWE
CWE-214
Published
7/15/2022
Updated
1/28/2023
KEV Status
No
Technology
TechnologyJava

Technical Details

CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Package NameEcosystemVulnerable VersionsFirst Patched Version
io.undertow:undertow-coremaven< 2.2.152.2.15

Vulnerability Intelligence
Miggo AIMiggo AI

Miggo AIRoot Cause Analysis

The vulnerability stems from two key issues: 1) In Http2Channel.java, the parseFrame method didn't properly handle continuation frames across multiple packets, as shown by the addition of a do-while loop in the patch to process continuation data. 2) In HpackEncoder.java, the encode method had incorrect iterator management that could leave headers unprocessed. The commit directly modifies these functions to add proper continuation frame handling and iterator advancement, aligning with the CWE-400 (Uncontrolled Resource Consumption) description. The test case H2CUpgradeContinuationTestCase added in the patch validates these fixes by forcing continuation frame scenarios.

Vulnerable functions

Only Mi**o us*rs **n s** t*is s**tion

WAF Protection Rules

WAF Rule

Un**rtow *li*nt si** invo**tion tim*out r*is** w**n **llin* ov*r *TTP*, t*is vuln*r**ility **n *llow *tt**k*r to **rry out **ni*l o* s*rvi** (*oS) *tt**ks in v*rsions l*ss t**n *.*.** *in*l.

Reasoning

T** vuln*r**ility st*ms *rom two k*y issu*s: *) In *ttp****nn*l.j*v*, t** p*rs**r*m* m*t*o* *i*n't prop*rly **n*l* *ontinu*tion *r*m*s **ross multipl* p**k*ts, *s s*own *y t** ***ition o* * *o-w*il* loop in t** p*t** to pro**ss *ontinu*tion **t*. *)