secure cookie attribute bypass with tab

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-80255
StatePUBLISHED
Assignercurl
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-06 18:17:22 UTC
Updated2026-09-06 18:17:22 UTC
DescriptionA `Set-Cookie:` header using tab (horizontal tab, ASCII code 9) instead of space (ascii code 32) immediately before the `Secure` attribute causes curl to store the cookie without its Secure flag. The cookie might then wrongfully be sent over plaintext HTTP on subsequent requests to the same host.

Risk And Classification

Problem Types: CWE-201 Information Exposure Through Sent Data

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Curl Curl affected 8.21.0 8.21.0 semver Not specified
CNA Curl Curl affected 8.20.0 8.20.0 semver Not specified
CNA Curl Curl affected 8.19.0 8.19.0 semver Not specified
CNA Curl Curl affected 8.18.0 8.18.0 semver Not specified
CNA Curl Curl affected 8.17.0 8.17.0 semver Not specified
CNA Curl Curl affected 8.16.0 8.16.0 semver Not specified
CNA Curl Curl affected 8.15.0 8.15.0 semver Not specified
CNA Curl Curl affected 8.14.1 8.14.1 semver Not specified
CNA Curl Curl affected 8.14.0 8.14.0 semver Not specified
CNA Curl Curl affected 8.13.0 8.13.0 semver Not specified

References

ReferenceSourceLinkTags
curl.se/docs/CVE-2026-80255.json 2499f714-1537-4658-8207-48ae4bb9eae9 curl.se
curl.se/docs/CVE-2026-80255.html 2499f714-1537-4658-8207-48ae4bb9eae9 curl.se
hackerone.com/reports/3972395 2499f714-1537-4658-8207-48ae4bb9eae9 hackerone.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Vendor Comments And Credit

Discovery Credit

CNA: Stanislav Fort (Aisle Research) (en)

CNA: Daniel Stenberg (en)

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