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HTTP Requests with X-Vercel-Set-Bypass-Cookie Header, (Tue, Apr 28th)

0
Medium
Vulnerabilityrce
Published: Tue Apr 28 2026 (04/28/2026, 13:28:45 UTC)
Source: SANS ISC Handlers Diary

Description

A few HTTP requests observed in a honeypot included the non-standard header "X-Vercel-Set-Bypass-Cookie," which is related to a Vercel feature allowing bypass of deployment protections by setting a cookie. This header is intended for testing and automation purposes to disable certain protections, such as web application firewalls, during CI/CD operations. The observed value "samesite-none-secure" is not documented by Vercel, raising concerns about potential misuse to relax security settings or expose secrets via cookies. No confirmed exploitation or vulnerability details are available, and the exact impact remains unclear.

AI-Powered Analysis

Machine-generated threat intelligence

AILast updated: 04/28/2026, 13:36:42 UTC

Technical Analysis

The threat involves HTTP requests containing the "X-Vercel-Set-Bypass-Cookie" header, which is linked to a Vercel feature that sets a cookie to maintain a protection bypass state. This feature is designed to facilitate testing by disabling certain security protections temporarily. The header value observed in the wild includes an undocumented option "samesite-none-secure," which may indicate attempts to weaken cookie security attributes. The requests were sent via an open proxy, likely to obscure the attacker's origin. There is no evidence of active exploitation or vulnerability in Vercel's platform based on the available information.

Potential Impact

The impact is currently theoretical and limited to the potential misuse of a legitimate bypass feature intended for testing. If abused, it could allow an attacker to bypass certain deployment protections or security controls temporarily. However, no known exploits or confirmed vulnerabilities have been reported. The undocumented header value could potentially relax cookie security policies, but no direct evidence of data exposure or compromise is available.

Mitigation Recommendations

No official patch or fix is indicated or required as this is a documented feature intended for testing. Organizations using Vercel should ensure that bypass headers and cookies are not exposed or accepted in production environments unintentionally. Monitoring for unusual use of such headers and restricting their acceptance to trusted sources or environments is recommended. Patch status is not applicable; check Vercel's official documentation for updates on deployment protection features.

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Technical Details

Article Source
{"url":"https://isc.sans.edu/diary/rss/32930","fetched":true,"fetchedAt":"2026-04-28T13:36:34.833Z","wordCount":411}

Threat ID: 69f0b7e2cbff5d8610142b39

Added to database: 4/28/2026, 1:36:34 PM

Last enriched: 4/28/2026, 1:36:42 PM

Last updated: 4/29/2026, 12:10:41 AM

Views: 10

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