CVE-2026-4437Disclosure(gnu / glibc)

LOWCVSS 7.5 · HIGH

Exploit discussion active in current signal (1 latest mentions)

Immediate actions

Hunt for exploitation attempts and persistence artifacts
Increase monitoring for publicly documented tradecraft
Track advisory updates for patch or workaround availability

Recommended action window: High priority (within 72h)

NVD description

Calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C Library version 2.34 to version 2.43 could, with a crafted response from the configured DNS server, result in a violation of the DNS specification that causes the application to treat a non-answer section of the DNS response as a valid answer.

gnu CVEs Back to dashboard

1.5/ 10 priority

Sources & remediation

Patch / fix

https://sourceware.org/bugzilla/show_bug.cgi?id=34014

Exploit / PoC references

https://sourceware.org/bugzilla/show_bug.cgi?id=34014

Other references

https://cert-portal.siemens.com/productcert/html/ssa-082556.html

Weakness type (CWE)

CWE-125

Priority

LOW

Exploitation

NONE

PoC

YES

Patch

AVAILABLE

Momentum

STABLE

Are you affected?

If you run products in this scope, you should treat this CVE as relevant to your environment.

glibc

Threat summary

Public PoC is present in monitored signal
5 mentions across 4 observed days
Momentum state: stable

What's happening

PoC mentioned or linked in 1 signal
Technical details provided in 2 signals
Disclosure: 2 classified signals
General: 2 classified signals
Peaked 3d ago at 2 mentions (2026-03-21); latest day: 1
5 total mentions across 4 days

Affected systems

Vendors

gnu

Products

glibc

Deep dive

Activity timeline5 mentions / 4d

Signal classification3 categories

Disclosure

240.0%

General

240.0%

PoC

120.0%

Referenced assets4 URLs

By indicator

Classification over time

Date	Total	Labels

2026-03-21	2	Disclosure1General1
2026-03-24	1	Disclosure1
2026-03-30	1	General1
2026-09-04	1	PoC1

Full discourse5 posts

Open Source Security mailing list@oss_security199d
Disclosure
2 CVEs in glibc https://www.openwall.com/lists/oss-security/2026/03/23/2 CVE-2026-4437,GLIBC-SA-2026-0005: gethostbyaddr and gethostbyaddr_r may incorrectly handle DNS response CVE-2026-4438,GLIBC-SA-2026-0006: gethostbyaddr and gethostbyaddr_r return invalid DNS hostnames
Post summary
Openwall announces two new glibc CVEs that impact gethostbyaddr and gethostbyaddr_r, describing incorrect DNS response handling and invalid hostname returns.
020722.3K
4.4K followersView on X
frances@BPJupiter35d
PoC
recreated CVE-2026-4437 :) https://t.co/aRwl6huVar
Post summary
The user indicates they have recreated CVE-2026-4437 and shared a link, but no additional exploitation or patch information is provided.
10110262
204 followersView on X
CERT-PY@CERTpy192d
General
⚠️ Vulnerabilidad en productos GNU ❗ CVE-2026-4437 ➡️ Más info: https://www.cert.gov.py/vulnerabilidad-en-productos-gnu-2/ https://t.co/NWJcUs9NeB
Post summary
The tweet simply announces the existence of CVE‑2026‑4437 in GNU products and provides a link for more information without detailing the vulnerability, patches, or exploitation status.
10010206
6.6K followersView on X
Infoflowcloud@infoflowcloud202d
Disclosure
🚨*CVE* CVE-2026-4437 Calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C Library version 2.34 to version 2.43 coul… https://www.cve.org/CVERecord?id=CVE-2026-4437 ----- Traducción: CVE-2026-4437 Lla… http://infoflow.cloud`
Post summary
The post announces CVE-2026-4437, provides a brief technical description of the affected glibc functions and versions, and links to the official CVE record. No exploit, mitigation, or active exploitation details are included.
0000030
61 followersView on X
CVE@CVEnew202d
General
CVE-2026-4437 Calling gethostbyaddr or gethostbyaddr_r with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C Library version 2.34 to version 2.43 coul… https://www.cve.org/CVERecord?id=CVE-2026-4437
Post summary
The snippet references CVE-2026-4437 with a brief mention of affected functions and library versions, but it provides no actionable details, proofs of concept, exploitation reports, or patch information.
00000247
56.8K followersView on X

CPE platform detail1 entries

Part:

Vendor:

Product:

Version:

Target SW:

Target HW:

1 of 1 entries

Part	Vendor	Product	Version	Target SW	Target HW
App	gnu	glibc	-	-	-

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What researchers are saying

CVE-2026-4437

Open Source Security mailing list@oss_securityDisclosure

Openwall announces two new glibc CVEs that impact gethostbyaddr and gethostbyaddr_r, describing incorrect DNS response handling and invalid hostname returns.

frances@BPJupiterPoC

The user indicates they have recreated CVE-2026-4437 and shared a link, but no additional exploitation or patch information is provided.

CERT-PY@CERTpyGeneral

The tweet simply announces the existence of CVE‑2026‑4437 in GNU products and provides a link for more information without detailing the vulnerability, patches, or exploitation status.

Infoflowcloud@infoflowcloudDisclosure

The post announces CVE-2026-4437, provides a brief technical description of the affected glibc functions and versions, and links to the official CVE record. No exploit, mitigation, or active exploitation details are included.

CVE@CVEnewGeneral

The snippet references CVE-2026-4437 with a brief mention of affected functions and library versions, but it provides no actionable details, proofs of concept, exploitation reports, or patch information.