CVE-2026-87864
IMAP APPEND plus CRLF conversion command injection
Published Oct 20, 2026
CVSS 3.1 · 8.1 High
EPSS < 1%
KEV · Not listed
Description
Enabling `CURLOPT_CRLF` causes curl to advertise the raw input byte count in
the `IMAP APPEND {N}` literal while transmitting line-ending expanded data.
The server reads only $N$ bytes for the payload, causing the remaining
overflow bytes to be interpreted and executed as pipelined IMAP commands
within the authenticated session.
the `IMAP APPEND {N}` literal while transmitting line-ending expanded data.
The server reads only $N$ bytes for the payload, causing the remaining
overflow bytes to be interpreted and executed as pipelined IMAP commands
within the authenticated session.
Affected Products
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CVE record
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NVD configurations
No data
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Red Hat packages
No data
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OpenCVE enrichment
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
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| curl | curl | unaffected |
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No data.
No data.
| Vendor | Product | Versions | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Curl | Curl |
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Remediation
Tracking
Advisories
| Source | ID | Title |
|---|---|---|
 Ubuntu USN |
USN-8927-1 | curl vulnerabilities |
| Ubuntu USN |
USN-8932-1 | curl vulnerabilities |
| Ubuntu USN |
USN-8927-2 | curl vulnerabilities |
Metrics
No CVSS v4.0
Attack Vector Network
Attack Complexity High
Privileges Required None
Scope Unchanged
Confidentiality Impact High
Integrity Impact High
Availability Impact High
User Interaction None
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.828% probability within 30 days)
Exploitation poc
Automatable no
Technical Impact total
References
History
Oct 30, 2026 12:30 PM
Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
cvssV3_1
|
ssvc
|
Oct 20, 2026 8:30 PM
Description updated. Title updated. Added references
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Description | A flaw was found in curl. When curl is configured to perform carriage return and line feed (CRLF) conversion during an Internet Message Access Protocol (IMAP) append operation, it incorrectly reports the raw input size rather than the expanded byte count. Because the receiving server only reads the advertised length as message data, it interprets the remaining overflow bytes as subsequent commands. An attacker capable of supplying message data with line breaks can exploit this issue to execute unauthorized IMAP commands within an authenticated session. | Enabling `CURLOPT_CRLF` causes curl to advertise the raw input byte count in the `IMAP APPEND {N}` literal while transmitting line-ending expanded data. The server reads only $N$ bytes for the payload, causing the remaining overflow bytes to be interpreted and executed as pipelined IMAP commands within the authenticated session. |
| Title | curl: IMAP APPEND plus CRLF conversion command injection | IMAP APPEND plus CRLF conversion command injection |
| References |
|
Oct 18, 2026 3:00 PM
First appearance in the feed. Affected vendors updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Curl
Curl curl |
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| Vendors & Products |
Curl
Curl curl |
Oct 17, 2026 12:30 AM
Description updated. Title updated. Weaknesses updated. Added references. Scoring metrics updated
View changes
| Type | Values Removed | Values Added |
|---|---|---|
| Description | A flaw was found in curl. When curl is configured to perform carriage return and line feed (CRLF) conversion during an Internet Message Access Protocol (IMAP) append operation, it incorrectly reports the raw input size rather than the expanded byte count. Because the receiving server only reads the advertised length as message data, it interprets the remaining overflow bytes as subsequent commands. An attacker capable of supplying message data with line breaks can exploit this issue to execute unauthorized IMAP commands within an authenticated session. | |
| Title | curl: IMAP APPEND plus CRLF conversion command injection | |
| Weaknesses | CWE-130 | |
| References |
| |
| Metrics |
threat_severity
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cvssV3_1
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Weaknesses