CVE Intelligence
High Input validation

CVE-2026-57210 — Heimdall: IP Spoofing via Unvalidated Forwarding Headers

Heimdall is a cloud native Identity Aware Proxy and Access Control Decision service. Prior to version 0.17.17, when the trusted_proxies option is configured, heimdall extracts client IP addresses from the Forwarded (for= parameter) and X-Forwarded-For headers and exposes them as Request.ClientIPAddresses to the rule pipeline. However, extracted values are not validated to be syntactically valid IP addresses. Arbitrary strings, malformed IP literals, and RFC 7239 unknown values and obfuscated identifiers are accepted without further checks. In addition, the Forwarded header parser splits on , and ; without accounting for RFC 7239 quoted strings, which can cause a single quoted value to be parsed as multiple entries, with fragments — including trailing quote characters — treated as independent addresses. This issue has been patched in version 0.17.17.

Published Oct 23, 2026 · Updated Oct 29, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP, GitHub Security Advisories · CNA: GitHub_M

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • EPSS 0.3% (30-day exploitation probability)+4
  • Technical severity (high)+6
  • Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
0.31%
ahead of 24% of scored CVEs · Oct 30, 2026
Affects
Dadrus
Heimdall and 1 more
CVSS base
7.0
High · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
Yes
can an attacker script the kill-chain steps
Technical impact
Partial
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

  • Go Https://github.com/dadrus/heimdall: fixed in version 0.17.17 — github.com (GitHub Security Advisories)

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Dadrus Heimdall, Go Https://github.com/dadrus/heimdall).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. Apply the fixed version or the patch documented under Remediation.
  4. Search available logs for exploit probes matching the vulnerability class (input validation), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Dadrus Heimdall version < 0.17.17 Vulnerable CVE Program (cve.org) e CISA ADP
Go Https://github.com/dadrus/heimdall ≤ 0.17.16 Vulnerable GitHub Security Advisories

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Attack requirements
Present
Privileges required
None
User interaction
None
Scope
X
Confidentiality (vulnerable system)
None
Integrity (vulnerable system)
None
Availability (vulnerable system)
None
Confidentiality (subsequent)
High
Integrity (subsequent)
High
Availability (subsequent)
None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
7.0 CVSS 4.0 High — — security-advisories@github.com via NIST National Vulnerability Database
7.0 CVSS 4.0 High — — GitHub_M via CVE Program (cve.org) e CISA ADP
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X (score shown at the top: security-advisories@github.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-20 · Improper Input Validation

Other CVEs with this weakness →

EPSS over time FIRST

Oct 24, 2026 → Oct 30, 2026 · 7 reading(s) · max 0.42%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

  • 2026
  • SSVC assessment updated
    Oct 29, 2026 · CVE Program (cve.org) e CISA ADP
  • Source status changed · Received → Deferred
    Oct 23, 2026 · NIST National Vulnerability Database
  • Fix documented
    Oct 23, 2026 · GitHub Security Advisories
  • Affected products added · go/https://github.com/dadrus/heimdall
    Oct 23, 2026 · GitHub Security Advisories
  • Affected products added · dadrus/heimdall
    Oct 23, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 23, 2026
  • CVSS changed · 7.0
    Oct 23, 2026 · NIST National Vulnerability Database
  • Source status changed · → Received
    Oct 23, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 23, 2026 · Alertas do Telegram
  • CVE published
    Oct 23, 2026 · GitHub_M

Source activity

Repeated readings are counted rather than listed.

  • 2× References added · Oct 23, 2026 – Oct 23, 2026
  • 1× Official description updated · Oct 23, 2026 – Oct 23, 2026

References

3 on the record

Elsewhere on this site

Dadrus
every CVE for this vendor
Input validation
same class
CWE-20
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-57209 Heimdall: Forwarded Header Injection via Unsanitized Host Header in Proxy Mode 7d
  • CVE-2026-42274 Heimdall: Authorization bypass via path normalization mismatch May 8, 2026
  • CVE-2026-42272 Heimdall: Case-sensitive handling of URL-encoded slashes may lead to inconsistent path interpretation May 8, 2026
  • CVE-2026-42273 Heimdall: Case-sensitive host matching may lead to policy bypass May 8, 2026
  • CVE-2026-32811 Heimdall: Path received via Envoy gRPC corrupted when containing query string Mar 19, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-57210 is "Heimdall: IP Spoofing via Unvalidated Forwarding Headers", rated High. It affects Heimdall (Dadrus); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 7.0 describes technical severity. EPSS 0.31% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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