CVE-2026-63771Public exploitNetwork attack vector

Session cookie theft via unescaped forwarded prefix

Published Jul 20, 2026 · Updated Jul 20, 2026

Cookie attribute injection in Adminer before 5.4.3 allows remote attackers to expose session cookies through X-Forwarded-Prefix. Adminer prepends the unvalidated header to REQUEST_URI, then cookie() interpolates that tainted URI into Set-Cookie path attributes without escaping semicolon delimiters. Exploitation requires a reverse proxy that forwards attacker-controlled header values and victim interaction; injected Domain or SameSite attributes can disclose session and database-key cookies or enable cross-origin authenticated requests.

CVSS severity6.0
Medium
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Cookie attribute injection in Adminer before 5.4.3 allows remote attackers to expose session cookies through X-Forwarded-Prefix. Adminer prepends the unvalidated header to REQUEST_URI, then cookie() interpolates that tainted URI into Set-Cookie path attributes without escaping semicolon delimiters. Exploitation requires a reverse proxy that forwards attacker-controlled header values and victim interaction; injected Domain or SameSite attributes can disclose session and database-key cookies or enable cross-origin authenticated requests.

The record

CVE
CVE-2026-63771
Published
Jul 20, 2026
Updated
Jul 20, 2026
Vendor
Adminer
Product
Adminer
Classifications
CWE-807, CWE-113, CWE-20, T1539
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <5.4.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Adminer · Adminerversion=0 <5.4.3

Published CVSS scores

6.0VulnCheckCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N
6.9GitHubCVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:N
7.1VulnCheckCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-807Reliance on Untrusted Inputs in a Security Decision
CWE-113Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting')
CWE-20Improper Input Validation
T1539Steal Web Session Cookie

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo