CVE-2020-26547Network attack vector

Message-history injection via unverified stanza senders

Published Feb 1, 2021 · Updated Aug 4, 2024

Improper sender verification in Monal before 4.9 allows remote attackers to inject forged messages into a victim's local history. Handlers for MAM and Message Carbon (XEP-0280) results accept sender and receiver identity data without verifying that the stanza's origin is authorized to assert it. An attacker must be able to send stanzas to the victim; successful exploitation falsifies displayed conversation history with attacker-chosen identities.

CVSS severity9.8
Critical
EPSS probability0.55%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper sender verification in Monal before 4.9 allows remote attackers to inject forged messages into a victim's local history. Handlers for MAM and Message Carbon (XEP-0280) results accept sender and receiver identity data without verifying that the stanza's origin is authorized to assert it. An attacker must be able to send stanzas to the victim; successful exploitation falsifies displayed conversation history with attacker-chosen identities.

The record

CVE
CVE-2020-26547
Published
Feb 1, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-345, T1565.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 1, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:P/A:N
9.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

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 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 exploitUnconfirmed

Weakness, pattern, technique

CWE-345Insufficient Verification of Data Authenticity
T1565.001Stored Data Manipulation

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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