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mod_qos CVE-2026-114459

| EUVDEUVD-2026-108023 LOW
Out-of-bounds Read (CWE-125)
2026-10-22 patrick@puiterwijk.org GHSA-j73g-g378-q257
3.7
CVSS 3.1 · Vendor: puiterwijk
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Reach Apache deploying mod_qos response inspection
  2. Exploit
    Induce crafted/malformed HTTP response
  3. Execution
    Trigger out-of-bounds read (CWE-125) in body inspection
  4. Impact
    Crash Apache worker process (DoS)

Vulnerability Assessment

Weakness
CWE
ASVS 5.0
V15 - Secure Coding and Architecture Bounds checking, read limits
MITRE ATT&CK

1 technique across 1 tactic: Collection

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires mod_qos to be configured to inspect HTTP response bodies (response-side content/QoS filtering must be enabled - not a default posture), and the attacker must be able to cause the server to emit specifically crafted/malformed responses, which in practice means a deployment where response content is attacker-influenced (e.g., mod_qos fronting a backend the attacker can manipulate). Limiting factors: the module itself is optional and uncommon, the response-inspection feature must be turned on, AC:H reflects the non-trivial crafting needed to trigger the out-of-bounds read, and impact is confined to availability (a single worker crash, A:L) with no data exposure. No authentication is required (PR:N) and no user interaction is needed (UI:N).

Impact

This is a genuinely low-priority issue despite being network-reachable and unauthenticated. The provided CVSS 3.1 vector (AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L) scores only 3.7 (Low), and the signals are internally consistent: the sole impact is availability (A:L) - an Apache worker process crash - with no confidentiality or integrity impact (C:N/I:N). AC:H correctly reflects that exploitation is not trivial: the attacker must induce specifically crafted server responses while mod_qos is inspecting response bodies. No EPSS score, CISA KEV listing, or POC indicator was supplied in the input, so there is no public exploit identified at time of analysis and no evidence of active exploitation. The tag set lists 'Information Disclosure' and 'Buffer Overflow', but these conflict with the authoritative data: the CWE is CWE-125 (out-of-bounds READ, not a write/overflow), and the CVSS sets C:N with the description describing only a DoS crash - so treat the info-disclosure characterization as unconfirmed. Bottom line: a real but minor availability bug that merits patching in the normal maintenance cycle, not emergency response.

Exploit ScenarioDerived

An attacker who can influence or control the content of HTTP responses passing through an Apache server running mod_qos with response-body inspection enabled (for example a reverse-proxy or content-filtering deployment with an attacker-influenced backend) crafts a malformed response. When mod_qos inspects the response body, improper boundary checking causes an out-of-bounds read that crashes the serving Apache worker process, producing a denial of service. No public exploit code is identified in the provided data, and the high attack complexity (AC:H) makes reliable triggering non-trivial.

Monitor Track and reassess. Why: LOW severity (CVSS 0.1-3.9).
No patch listed yet 0.3% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 22, 2026

Denial of service in mod_qos can crash an Apache worker process when the module inspects HTTP response bodies and processes a specifically crafted server response. The flaw is an out-of-bounds read (CWE-125) reachable by unauthenticated remote attackers, but exploitation requires the non-default response-body inspection feature and a deployment where response content is attacker-influenced, so practical risk is low. No public exploit or CISA KEV listing was identified in the provided data.

RemediationAI

No vendor-released patch was identified in the provided data; monitor the Red Hat CVE page and Bugzilla 2558397 for updated fixed packages or module releases. Until a fix is available, disable mod_qos response-body inspection to remove the vulnerable code path, accepting the loss of response-side QoS/content filtering. If response inspection is not essential, unload mod_qos entirely to eliminate all module attack surface, at the cost of losing its connection and request QoS controls. Where response inspection must remain enabled, restrict the module to trusted, well-formed backend responses and prevent attacker-controlled content from flowing through the inspected path; this reduces exposure but does not remediate the underlying out-of-bounds read.

Affected VersionsENISA

mod_qos 11.76
mod_qos 11.74
mod_qos 11.79

Affected Packages

euvd mod_qos no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

mod_qos is an optional third-party module for Apache HTTP Server that provides quality-of-service controls, connection and request limiting, and optional inspection of HTTP response bodies. The root cause is CWE-125 (out-of-bounds read): improper boundary checking while parsing response bodies allows the module to read past allocated buffer boundaries, causing an Apache worker process to crash. The CVSS vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L reflects network reachability without authentication or user interaction, but high attack complexity because the response-inspection feature must be enabled and the attacker must be able to induce specifically malformed or crafted server responses. Impact is confined to availability (single worker crash); the assessed vector has no confidentiality or integrity impact, even though source tags include information disclosure. The provided data does not include CPE identifiers or affected version ranges.

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Severity by source

Vendor (puiterwijk) PRIMARY 3.7 LOW
AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
vuln.today AI 3.7 LOW

Unauthenticated and network-reachable (PR:N/AV:N) but requires crafted responses plus response-inspection config (AC:H); out-of-bounds read only crashes a worker, so C:N/I:N and A:L.

3.1 AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:L
4.0 AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N

Primary rating from Vendor (puiterwijk).

CVSS VectorVendor: puiterwijk

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

DescriptionCVE.org

A flaw was found in mod_qos. When inspecting HTTP response bodies, improper boundary checking can cause the module to read memory outside allocated buffer boundaries. An unauthenticated remote attacker can exploit this vulnerability by triggering specifically crafted server responses, causing an Apache worker process to crash and resulting in a Denial of Service (DoS).

Threat Intelligence Overview

EPSS Score
0.3%
Top 81% exploitable
Prevalence
Low
mod_qos is an optional third-party Apache module, not enabled by default
Social Media
1
Sightings
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity LOW
CISA KEV No
Public POC No
EPSS 0.3%
Patch available No
Active threat No
Deciding rule
LOW severity (CVSS 0.1-3.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Defer
Exploitation· derived
None
System Exposure· derived
Open
Automatable· derived
No
Human Impact· derived
Low

Priority Score

18
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +18
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

A buffer overflow occurs when a program writes more data to a memory buffer than it was allocated to hold, causing the excess data to spill into adjacent memory regions.

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

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