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01 Record

CVE-2026-23829

Mailpit has SMTP Header Injection via Regex Bypass

MediumPUBLISHEDCNA: GitHub_M
CNA base score5.3 CVSS v3.xCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

02 Description

Mailpit has SMTP Header Injection via Regex Bypass

03 Exploitation and scoring

Exploitation
Public exploit code exists. CISA's assessment records a public proof of concept. That is not a report of exploitation in the wild.
SSVC decision
  • ExploitationpocPublic proof-of-concept exploit code exists. Not a report of exploitation in the wild.
  • AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
1.40% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 71.9% of scored records. A rank, not a probability.
NVD base score
5.3 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
NVD analysis status
Analyzed. NVD last modified this record on 2026-06-17.
Red Hat severity
No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-01-18 23:23Z9 MO AGO
Last updated
2026-01-20 20:08Z9 MO AGO
Reserved
2026-01-16
Assigning CNA
GitHub_M
Record state
PUBLISHED
Severity
Medium (CVSS 5.3)
CNA CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N
Weaknesses
  • CWE-93Improper Neutralization of CRLF Sequences ('CRLF Injection')Base
  • CWE-150Improper Neutralization of Escape, Meta, or Control SequencesVariant
Data version
5.2
Document digest
b1bddfb90164e944492ec6b93a26f19e294f9a92375bc64ed2ca1b0e63d0f609

05 Affected products

VendorProductVersionsPlatforms
axllentmailpit< 1.28.3—

06 References