Adminer 4.6.0 through 5.5.0 (fixed in 5.5.1) contains an incomplete fix for a prior X-Forwarded-Prefix vulnerability (GHSA-8478-xrj3-h9c2). The validation guard (bootstrap.inc.php) only rejects prefixes matching ^/[^/], blocking //evil.com but allowing values such as /\evil.com whose second character is a backslash. Because browsers normalize backslash to forward slash, a network-path reference survives into REQUEST_URI and reaches cookie_path(), affecting the Set-Cookie Path attribute. Exploitation requires that clients can set the X-Forwarded-Prefix header (a misconfigured or absent reverse proxy). Impact is limited to anomalous cookie-path scoping.
CVE-2026-16434
This low-severity CVE scores 2.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.3%, top 78% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- Lower severity and no public exploit yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 2.3
- EG Score
- 2.3(medium)
- EG Risk
- 41(Attend)EG Risk 41/100SSVC: Attend
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity23% × 45%Exploitation40% × 40%Automatability100% × 15%Action: Remediate soon — notable exploitation risk. - EPSS PROB
- 0%
- EPSS %ILE
- 22%
- KEV
- Not listed
Published
August 25, 2026
Last Modified
August 27, 2026
References (3)
- disclosure@vulncheckhttps://github.com/vrana/adminer/security/advisories/GHSA-fr74-9mf9-gf44
- disclosure@vulncheckhttps://www.vulncheck.com/advisories/adminer-before-x-forwarded-prefix-backslash-bypass
- 134c704f-9b21-4f2e-91b3-4a467353bcc0https://github.com/vrana/adminer/security/advisories/GHSA-fr74-9mf9-gf44
Vendor Advisories for CVE-2026-16434(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 12× in last 7d / 12× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-08-30 01:22 UTCEPSS rescore
- 2026-08-28 21:41 UTCEPSS rescore
- 2026-08-27 17:21 UTCEG score recompute
- 2026-08-27 17:21 UTCGHSA enrichment
- 2026-08-27 17:14 UTCEG score recompute
- 2026-08-27 17:14 UTCGHSA enrichment
- 2026-08-27 14:25 UTCEPSS rescore
- 2026-08-26 14:46 UTCEPSS rescore
- 2026-08-25 13:48 UTCEPSS rescore
- 2026-08-25 02:19 UTCEG score recompute
- 2026-08-25 01:50 UTCEG score recompute
- 2026-08-25 01:50 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Same CWE
10 shownCWE-20
- CVE-2005-0050EG 10.0EPSS p99HIGH
- CVE-2004-1019EG 10.0EPSS p94HIGH
- CVE-2004-0840EG 10.0EPSS p98HIGH
- CVE-2003-1425EG 10.0EPSS p96HIGH
- CVE-2003-1487EG 10.0EPSS p94HIGH
- CVE-2002-1874EG 10.0HIGH
- CVE-2002-2236EG 10.0EPSS p91HIGH
- CVE-2002-2365EG 10.0HIGH
- CVE-2002-1358EG 10.0EPSS p93HIGH
- CVE-2002-1359EG 10.0EPSS p100HIGH
Frequently asked(5)
What is CVE-2026-16434?
When was CVE-2026-16434 disclosed?
Is CVE-2026-16434 actively exploited?
What is the CVSS score of CVE-2026-16434?
How do I remediate CVE-2026-16434?
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-16434
Is Your Infrastructure Affected by CVE-2026-16434?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.