CVE-2025-27913Network attack vector

Malicious email links via Host header fallback

Published Mar 10, 2025 · Updated Mar 11, 2025

Host header injection in Passbolt API before 5 allows remote attackers to place attacker-chosen domains in generated email links. When App.fullBaseUrl is unset, the URL Router falls back to PHP's HTTP_HOST value, which can derive directly from the request's Host header. Exposure requires a misconfigured server and an unauthenticated email-generating endpoint; further exploitation requires a recipient to click the malicious link.

CVSS severity2.1
Low
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Host header injection in Passbolt API before 5 allows remote attackers to place attacker-chosen domains in generated email links. When App.fullBaseUrl is unset, the URL Router falls back to PHP's HTTP_HOST value, which can derive directly from the request's Host header. Exposure requires a misconfigured server and an unauthenticated email-generating endpoint; further exploitation requires a recipient to click the malicious link.

The record

CVE
CVE-2025-27913
Published
Mar 10, 2025
Updated
Mar 11, 2025
Vendor
Passbolt
Product
Passbolt API
Classifications
CWE-348, T1566.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 10, 2025CVE publishedPublication date reported by the CVE source.
  2. Mar 11, 2025Record 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 <5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Passbolt · Passbolt APIversion=0 <5

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
2.1MITRECVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:L/SA: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 exploitUnconfirmed

Weakness, pattern, technique

CWE-348Use of Less Trusted Source
T1566.002Spearphishing Link

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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