CVE-2026-125756 PUBLISHED

postal-mime before 4.2.1 Sender Spoofing via Address Parser Domain Truncation

Assigner: VulnCheck
Reserved: 10.11.2026 Published: 10.11.2026 Updated: 10.11.2026

postal-mime before 4.2.1 contains a parser differential vulnerability in its address parser that truncates the domain at folding whitespace or comments preceding a dot. Remote attackers can craft From headers that pass SPF/DKIM/DMARC alignment for their own subdomain while PostalMime.parse() reports a spoofed victim sender address.

CVSS Vector: CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CVSS Score: 8.2

Exploitability Metrics		Vulnerable System Impact Metrics		Subsequent System Impact Metrics
Attack Vector	Network	Confidentiality	None	Confidentiality	None
Attack Complexity	High	Integrity	High	Integrity	None
Attack Requirements	Present	Availability	None	Availability	None
Privileges Required	None
User Interaction	None

CVSS 4.0

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
CVSS Score: 5.9

Attack Vector	Network	Scope	Unchanged
Attack Complexity	High	Confidentiality Impact	None
Privileges Required	None	Integrity Impact	High
User Interaction	None	Availability Impact	None

CVSS 3.1

Product Status

Vendor	postalsys
Product	postal-mime
Versions	Default: unaffected affected from 0 to 4.2.1 (excl.)

CVE-2026-125756 PUBLISHED

postal-mime before 4.2.1 Sender Spoofing via Address Parser Domain Truncation

Metrics

Product Status

Credits

References

Problem Types