How severe is CVE-2026-63771?

CVE-2026-63771 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity low, and availability none.

Is CVE-2026-63771 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (16th percentile), an estimate of the probability of exploitation in the next 30 days.

How do I fix CVE-2026-63771?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-63771 published?

CVE-2026-63771 was published on 2026-07-20 and last updated on 2026-07-23.

CVE-2026-63771

CVE-2026-63771 is a high-severity vulnerability with a CVSS 3.x base score of 7.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-113.

Key facts

Severity: High (CVSS 3.x base score 7.1)
CVSS v4: 6.0
EPSS exploit prediction: 0% (16th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-113
Published: 2026-07-20
Last modified: 2026-07-23

Description

Adminer before 5.4.3 contains a cookie injection vulnerability that allows attackers to manipulate cookie attributes by injecting arbitrary values through the unsanitized X-Forwarded-Prefix HTTP header used in Set-Cookie path attributes. Attackers can exploit a misconfigured reverse proxy to downgrade SameSite protection and enable cross-origin authenticated requests, bypassing cookie security controls.

Frequently asked questions

What is CVE-2026-63771?: Adminer before 5.4.3 contains a cookie injection vulnerability that allows attackers to manipulate cookie attributes by injecting arbitrary values through the unsanitized X-Forwarded-Prefix HTTP header used in Set-Cookie path attributes. Attackers can exploit a misconfigured reverse proxy to downgrade SameSite protection and enable cross-origin authenticated requests, bypassing cookie security controls.
How severe is CVE-2026-63771?: CVE-2026-63771 has a CVSS 3.x base score of 7.1, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is high, integrity low, and availability none.
Is CVE-2026-63771 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (16th percentile), an estimate of the probability of exploitation in the next 30 days.
How do I fix CVE-2026-63771?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-63771 published?: CVE-2026-63771 was published on 2026-07-20 and last updated on 2026-07-23.

References

Other CWE-113 (HTTP Response Splitting) vulnerabilities

CVE-2026-67289 — Critical (CVSS 9.8): FreeRDP before 3.29.0 (affected versions <= 3.28.0) does not validate CRLF and control characters in the…
CVE-2026-38967 — Critical (CVSS 9.8): CrowCpp Crow through v1.3.1 HTTP is vulnerable to response header injection via unvalidated response header values.
CVE-2026-34520 — Critical (CVSS 9.1): AIOHTTP is an asynchronous HTTP client/server framework for asyncio and Python. Prior to version 3.13.4, the C parser…
CVE-2025-53007 — High (CVSS 8.9): arduino-esp32 provides an Arduino core for the ESP32. Versions prior to 3.3.0-RC1 and 3.2.1 contain a HTTP Response…
CVE-2024-52875 — High (CVSS 8.8): An issue was discovered in GFI Kerio Control 9.2.5 through 9.4.5. The dest GET parameter passed to the…
CVE-2018-0689 — High (CVSS 8.8): HTTP header injection vulnerability in SEIKO EPSON printers and scanners (DS-570W firmware versions released prior to…

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