NVD / CVE Program· CNA certcc

CVE-2026-4893: An information disclosure vulnerability in dnsmasq allows remote attackers to bypass source checks via a crafted DNS packet with RFC 7871 cl

Noroxi assessment

Priority: Monitor (action score 22/100)

Public proof-of-concept code exists (GitHub); there is no record of exploitation in the wild.
Probability of exploitation in the next 30 days: 1.7% (FIRST EPSS); higher than 78.1% 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.
According to CISA the attack is automatable: targets can be found by mass scanning.
Fixed version: azl3 dnsmasq 2.90-1 on Azure Linux 3.0 2.92-1; azl3 dnsmasq 2.92-1 on Azure Linux 3.0 2.92-1.

Low priority for now. Upgrade to azl3 dnsmasq 2.90-1 on Azure Linux 3.0 2.92-1; azl3 dnsmasq 2.92-1 on Azure Linux 3.0 2.92-1 or later.

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

An information disclosure vulnerability in dnsmasq allows remote attackers to bypass source checks via a crafted DNS packet with RFC 7871 client subnet information.

MediumCVSS 5.3 · v3.1—Proof of concept Fix available

Published: May 11, 2026
Updated: Jun 17, 2026
EPSS: 1.7% · 78th percentile
CWE: CWE-287

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 21 / 40 · 5.3 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 1 / 30 · 1.7%

CISA SSVC decision

Exploitation: none
Automatable: yes
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
Proof of concept exists, no weaponized module
A fix has been released

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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.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (certcc). Independent of NVD's CPE analysis and usually ahead of it.

dnsmasq dnsmasq
- before 2.92rel2affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
AlmaLinux:10	dnsmasq	before 2.90-7.el10_2	2.90-7.el10_2
AlmaLinux:10	dnsmasq-utils	before 2.90-7.el10_2	2.90-7.el10_2
AlmaLinux:8	dnsmasq	before 2.79-36.el8_10	2.79-36.el8_10
AlmaLinux:8	dnsmasq-utils	before 2.79-36.el8_10	2.79-36.el8_10
AlmaLinux:9	dnsmasq	before 2.85-18.el9_8.1	2.85-18.el9_8.1
AlmaLinux:9	dnsmasq-utils	before 2.85-18.el9_8.1	2.85-18.el9_8.1
Alpine:v3.22	dnsmasq	before 2.91-r1	2.91-r1
Alpine:v3.24	dnsmasq	before 2.92_p2-r0	2.92_p2-r0
Debian:12	dnsmasq	before 2.90-4~deb12u2	2.90-4~deb12u2
Debian:13	dnsmasq	before 2.91-1+deb13u1	2.91-1+deb13u1
Debian:14	dnsmasq	before 2.92-5	2.92-5
openSUSE:Tumbleweed	dnsmasq	before 2.92rel2-1.1	2.92rel2-1.1
Red Hat:enterprise_linux:10.2	dnsmasq	before 0:2.90-7.el10_2	0:2.90-7.el10_2
Red Hat:enterprise_linux:10.2	dnsmasq-debuginfo	before 0:2.90-7.el10_2	0:2.90-7.el10_2
Red Hat:enterprise_linux:10.2	dnsmasq-debugsource	before 0:2.90-7.el10_2	0:2.90-7.el10_2
Red Hat:enterprise_linux:10.2	dnsmasq-utils	before 0:2.90-7.el10_2	0:2.90-7.el10_2
Red Hat:enterprise_linux:10.2	dnsmasq-utils-debuginfo	before 0:2.90-7.el10_2	0:2.90-7.el10_2
Red Hat:enterprise_linux:8::appstream	dnsmasq	before 0:2.79-36.el8_10	0:2.79-36.el8_10
Red Hat:enterprise_linux:8::appstream	dnsmasq-debuginfo	before 0:2.79-36.el8_10	0:2.79-36.el8_10
Red Hat:enterprise_linux:8::appstream	dnsmasq-debugsource	before 0:2.79-36.el8_10	0:2.79-36.el8_10
Red Hat:enterprise_linux:8::appstream	dnsmasq-utils	before 0:2.79-36.el8_10	0:2.79-36.el8_10
Red Hat:enterprise_linux:8::appstream	dnsmasq-utils-debuginfo	before 0:2.79-36.el8_10	0:2.79-36.el8_10
Red Hat:enterprise_linux:9::appstream	dnsmasq	before 0:2.85-18.el9_8.1	0:2.85-18.el9_8.1
Red Hat:enterprise_linux:9::appstream	dnsmasq-debuginfo	before 0:2.85-18.el9_8.1	0:2.85-18.el9_8.1

+12

Same product

dnsmasq: all records

Other highest-scoring records for the same primary product.

CVE-2026-4892A heap-based out-of-bounds write vulnerability in the DHCPv6 implementation of dnsmasq allows local attackers to execute arbitrary code with
33Monitor
CVE-2026-4890A Denial of Service (DoS) vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a craft
33Monitor
CVE-2026-5172A buffer overflow in dnsmasq’s extract_addresses() function allows an attacker to trigger a heap out-of-bounds read and crash by exploiting
30Monitor

Published before and after this one in the same product

← EarlierCVE-2006-2017Apr 25, 2006 · Dnsmasq 2.29 allows remote attackers to cause a denial of service (application crash) via a DHCP client broadcast reply request.
21Monitor
← EarlierCVE-2026-2291May 11, 2026 · dnsmasqs extract_name() function can be abused to cause a heap buffer overflow, allowing an attacker to inject false DNS cache entries, whic
29Monitor
← EarlierCVE-2026-4891May 11, 2026 · A heap-based out-of-bounds read vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a
23Monitor

Remediation

Which version to upgrade to

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

Product / package	Fixed version	Source
azl3 dnsmasq 2.90-1 on Azure Linux 3.0	2.92-1 · CBL-Mariner Releases	Microsoft (MSRC)
azl3 dnsmasq 2.92-1 on Azure Linux 3.0	2.92-1 · CBL-Mariner Releases	Microsoft (MSRC)
almalinux:dnsmasq	2.90-7.el10_2 · AlmaLinux:10	Package registry (OSV)
almalinux:dnsmasq-utils	2.90-7.el10_2 · AlmaLinux:10	Package registry (OSV)
alpine:dnsmasq	2.91-r1 · Alpine:v3.22	Package registry (OSV)
debian:dnsmasq	2.90-4~deb12u2 · Debian:12	Package registry (OSV)
opensuse:dnsmasq	2.92rel2-1.1 · openSUSE:Tumbleweed	Package registry (OSV)
red hat:dnsmasq	0:2.90-7.el10_2 · Red Hat:enterprise_linux:10.2	Package registry (OSV)
red hat:dnsmasq-debuginfo	0:2.90-7.el10_2 · Red Hat:enterprise_linux:10.2	Package registry (OSV)
red hat:dnsmasq-debugsource	0:2.90-7.el10_2 · Red Hat:enterprise_linux:10.2	Package registry (OSV)
red hat:dnsmasq-utils	0:2.90-7.el10_2 · Red Hat:enterprise_linux:10.2	Package registry (OSV)
red hat:dnsmasq-utils-debuginfo	0:2.90-7.el10_2 · Red Hat:enterprise_linux:10.2	Package registry (OSV)
rocky linux:dnsmasq	0:2.90-7.el10_2 · Rocky Linux:10	Package registry (OSV)
suse:dnsmasq	2.92rel2-18.27.1 · SUSE:Linux Enterprise Server 12 SP5-LTSS	Package registry (OSV)

Exploit status

Proof of concept available

A public proof of concept or detection signature exists. Exploit knowledge is out there; don't delay patching.

Evidence

Proof-of-concept repository on GitHub ×1

Noroxi does not host or link to exploit code. Metasploit module names and Nuclei template ids are shown (names, not code); Exploit-DB entries and PoC repositories are given as counts only.

Public exploit evidence
Source	Kind	Date
Proof-of-concept repository on GitHub	stars:0	2026-05-27

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.

PublishedMay 11, 2026
First PoCMay 27, 2026+15 d
TodayOct 28, 2026+170 d

EPSS, last 120 days+1% in 7 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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.

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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: low · data can be read
Integrity: none
Availability: none

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

Weakness class (CWE)

CWE-287 · Improper Authentication

CVSS vector

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

nvd-secondary

Root cause

Authentication is added route by route instead of being enforced in one place. When a route added later bypasses the shared middleware, the session check never runs for it.

The bug in code

The whole CWE-287 class

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

Vulnerable

1app.use("/admin", requireSession, adminRouter);
2

3// Route added later skips the middleware
4app.post("/admin-api/config", updateConfig);

Fixed

1const admin = express.Router();
2admin.use(requireSession, requireRole("admin"));
3

4admin.post("/config", updateConfig);
5app.use("/admin", admin);

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

Change log

Fix✗ → ✓Sep 28, 2026, 10:45 PM UTC

For records you follow, these changes also arrive as notifications. →

References

github.com/NixOS/nixpkgs/pull/519082

Show all references (5 more)

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

All records

Noroxi analysis

What does it mean in your environment?

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Data sources and verification

CNA: certcc

CVE.org (CNA)May 20, 2026, 2:09 PM UTC
CISA ADPMay 20, 2026, 2:09 PM UTC
NVDJun 17, 2026, 6:57 AM UTC
FIRST EPSSOct 27, 2026, 12:00 AM UTC
OSV / GHSAOct 28, 2026, 3:18 AM UTC
MSRCOct 19, 2026, 3:24 AM UTC
PoC-in-GitHubOct 28, 2026, 3:18 AM UTC

Each line is when that source was last processed for this record.