CVE-2026-57511 superplanehq CVE debrief

Who should care

Defenders responsible for SuperPlane installations, security teams assessing vulnerability exposure, and developers integrating SuperPlane into their applications should be aware of this vulnerability and take necessary actions to mitigate the risk.

Why it matters

CVE-2026-57511 is a medium-severity vulnerability in SuperPlane before version 0.30.0 that allows unauthenticated SMTP header injection via webhook event payload titles. Defenders should prioritize verifying exposure, assessing potential impact, and upgrading to version 0.30.0 or later. The vulnerability's consequences could include content exfiltration, SPF/DKIM bypass, and phishing attacks. Evidence is based on official CVE and NVD records, as well as source references.

• Potential for content exfiltration via added Bcc recipients
• Possible bypass of SPF and DKIM checks through forged From addresses
• Risk of phishing attacks through corrupted message bodies
• Need for verification of SuperPlane version and exposure to this vulnerability

Technical summary

The SuperPlane before version 0.30.0 contains an SMTP header injection vulnerability. This vulnerability allows unauthenticated attackers to inject arbitrary SMTP headers by including CRLF sequences in the event payload title field delivered via webhook. The injected headers could be used to add Bcc recipients for content exfiltration, forge the From address to bypass SPF and DKIM checks, or inject Content-Type and MIME boundary headers to corrupt message bodies for phishing.

Defensive priority

Defenders should prioritize verifying exposure of SuperPlane installations to this SMTP header injection vulnerability and assess the potential for content exfiltration, SPF/DKIM bypass, or phishing attacks.

Recommended defensive actions

• Verify SuperPlane installations for exposure to this vulnerability
• Assess potential for content exfiltration, SPF/DKIM bypass, or phishing attacks
• Prioritize upgrading to SuperPlane version 0.30.0 or later
• Monitor for suspicious SMTP activity
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented.

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its description, CVSS score, and affected versions. However, the exact scope of affected deployments and potential impact require further verification.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.