CVE-2016-20011Network attack vector

Feed tampering via missing TLS verification

Published May 25, 2021 · Updated Aug 6, 2024

Improper certificate validation in libgrss through 0.7.0 allows remote attackers to manipulate downloaded feeds via unverified TLS connections. SoupSessionSync downloads feeds without enabling certificate verification, allowing man-in-the-middle attackers to alter feed contents undetected. Exploitation requires network access to feed traffic; impact is feed integrity manipulation without reported confidentiality or availability effects.

CVSS severity7.5
High
EPSS probability1.47%
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 libgrss through 0.7.0 allows remote attackers to manipulate downloaded feeds via unverified TLS connections. SoupSessionSync downloads feeds without enabling certificate verification, allowing man-in-the-middle attackers to alter feed contents undetected. Exploitation requires network access to feed traffic; impact is feed integrity manipulation without reported confidentiality or availability effects.

The record

CVE
CVE-2016-20011
Published
May 25, 2021
Updated
Aug 6, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-295, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 25, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 6, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.0NVDAV:N/AC:L/Au:N/C:N/I:P/A:N
7.5NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-295Improper Certificate Validation
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

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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