CVE-2026-1858Public exploitNetwork attack vector

TLS server impersonation via unchecked certificate purpose

Published Apr 29, 2026 · Updated Apr 29, 2026

Improper certificate validation in GNU Wget2 2.2.1 and earlier allows remote attackers to impersonate TLS servers using misissued certificates. Libwget's GnuTLS callback omits the TLS server-purpose check, its OpenSSL context does not set X509_PURPOSE_SSL_SERVER, and wolfSSL mishandles certificate errors. Exploitation requires a trusted certificate and private key with incompatible KU or EKU, enabling an impersonated endpoint to observe or alter downloaded data.

CVSS severity4.8
Medium
EPSS probability0.15%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in GNU Wget2 2.2.1 and earlier allows remote attackers to impersonate TLS servers using misissued certificates. Libwget's GnuTLS callback omits the TLS server-purpose check, its OpenSSL context does not set X509_PURPOSE_SSL_SERVER, and wolfSSL mishandles certificate errors. Exploitation requires a trusted certificate and private key with incompatible KU or EKU, enabling an impersonated endpoint to observe or alter downloaded data.

The record

CVE
CVE-2026-1858
Published
Apr 29, 2026
Updated
Apr 29, 2026
Vendor
The GnuPG Project
Product
Wget2
Classifications
CWE-20, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 29, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 29, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=2.2.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The GnuPG Project · Wget2version=0 <=2.2.1

Published CVSS scores

6.3SUSECVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
4.8SUSECVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
4.8Tenable Network Security, Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-20Improper Input Validation
T1557Adversary-in-the-Middle

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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