Cyber Resilience

CVE-2026-55430

Coder ≤ 2.29.17

Published
08 July 2026
Modified
08 July 2026
Patch / advisory
View advisory
CVSS Score v3.1 5.8
Click a component to see what it means
Raw vectorCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:N/A:N
EPSS Score 0.0021 11th percentile
Risk Priority 41 floored blend · peak EPSS

CVSS and EPSS are reproduced from their sources (NVD, FIRST EPSS). Risk Priority is our own derived reading, not an NVD score.

Summary

CVE-2026-55430 is a medium-severity Insufficient Verification of Data Authenticity (CWE-345) vulnerability in Coder Coder. Its CVSS base score is 5.8 (Medium).

Operationally, exploitation aligns with the MITRE ATT&CK technique Mark-of-the-Web Bypass (T1553.005); ranked at the 11th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified map to AC-16 (Security and Privacy Attributes) and AC-4 (Information Flow Enforcement) — see the control section below for these in your framework.

OWASP Top 10 for Web (2025)

A01:2025 Broken Access ControlA08:2025 Software or Data Integrity Failures

EU & UK References

Vulnerability Data

Coder allows organizations to provision remote development environments via Terraform. Prior to versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2, the workspace app proxy resolves the target app from `httpapi.RequestHost()` which prefers the `X-Forwarded-Host` header over the real `Host` header. No middleware…

more

strips `X-Forwarded-Host` before routing and the header is not browser-forbidden so client-side JavaScript can set it on `fetch()` calls. Practical exploitation requires subdomain app routing (wildcard hostname) enabled, a victim who visits the attacker's shared app and a deployment whose upstream proxy does not strip `X-Forwarded-Host`. The fix in versions 2.29.7, 2.32.7, 2.33.8, and 2.34.2 trusts `X-Forwarded-Host` only from configured trusted proxies and otherwise resolves the routing host from the verified request host. As a workaround, place an upstream reverse proxy that strips or overwrites `X-Forwarded-Host` on untrusted requests.

CWE(s)
CWE-345CWE-441

Related Threats

MITRE ATT&CK Enterprise Techniques

T1553.005 Mark-of-the-Web Bypass Defense Impairment
Adversaries may abuse specific file formats to subvert Mark-of-the-Web (MOTW) controls.
attack.mitre.org →
T1090 Proxy Command And Control
Adversaries may use a connection proxy to direct network traffic between systems or act as an intermediary for network communications to a command and control server to avoid direct connections to their infrastructure.
attack.mitre.org →
T1090.002 External Proxy Command And Control
Adversaries may use an external proxy to act as an intermediary for network communications to a command and control server to avoid direct connections to their infrastructure.
attack.mitre.org →
T1195 Supply Chain Compromise Initial Access
Adversaries may manipulate products or product delivery mechanisms prior to receipt by a final consumer for the purpose of data or system compromise.
attack.mitre.org →
T1195.001 Compromise Software Dependencies and Development Tools Initial Access
Adversaries may manipulate software dependencies and development tools prior to receipt by a final consumer for the purpose of data or system compromise.
attack.mitre.org →
T1195.002 Compromise Software Supply Chain Initial Access
Adversaries may manipulate application software prior to receipt by a final consumer for the purpose of data or system compromise.
attack.mitre.org →
Derived from this CVE’s CWE(s) via the direct CWE→ATT&CK cross-walk.

CVEs Like This One

CVE-2026-46354Same product: Coder Coder
CVE-2026-55432Same product: Coder Coder
CVE-2026-55433Same product: Coder Coder
CVE-2026-55438Same product: Coder Coder
CVE-2026-55431Same product: Coder Coder
CVE-2024-27918Same product: Coder Coder
CVE-2026-55427Same product: Coder Coder
CVE-2026-55075Same product: Coder Coder
CVE-2026-55437Same product: Coder Coder
CVE-2025-66411Same product: Coder Coder

Affected Assets

coder
coder
≤ 2.29.17 · 2.30.0 — 2.32.7 · 2.33.0 — 2.33.8

Mitigating Controls

Control response

Prevent
Stop it (NIST 800-53)

—

Detect
Catch it (NIST detect / respond)

—

Harden
Shrink the surface (DISA STIG)
  • 8 hardening rules · 5 OS baselines
Validate
Prove the fix (OWASP ASVS)
  • V3.5.5
  • V3.2.1
  • V3.5.1
  • V3.5.3

Mitigating Controls (NIST 800-53 r5) AI

SC-23 Session Authenticity good match

Explicit requirement to protect session authenticity structurally prevents the weakness for communications.

AC-16 Security and Privacy Attributes good match

Associating and preserving security attributes such as original source identity prevents the loss of provenance that creates the confused deputy.

AC-4 Information Flow Enforcement good match

Information flow enforcement requires preserving and checking source attributes before forwarding requests outside the trust boundary.

SI-7 Software, Firmware, and Information Integrity good match

Integrity verification tools detect (but do not stop) the acceptance of data lacking authenticity.

AC-3 Access Enforcement partial match

Access enforcement directly stops a component from acting on forwarded requests without verifying original source authorizations.

SC-13 Cryptographic Protection partial match

Cryptographic mechanisms can be used to verify authenticity, thereby preventing acceptance of invalid data.

Mitigating Controls (NIST CSF 2.0) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.

PR.AA-04 mostly match
prevents

Proper conveyance and verification of original identity assertions directly prevents loss of request source when forwarding.

RC.RP-05 mostly match
degrades

CWE-345 directly impairs RC.RP-05's verification of restored-asset integrity/authenticity, largely defeating the outcome while still leaving other restoration-confirmation steps partially viable.

PR.AA-05 partial match
prevents

Enforcing least-privilege authorizations on forwarded requests reduces confused-deputy abuse even if source identity is lost.

Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI

Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.

A.8.29 Security testing in development and acceptance mostly match
finds

Security testing can detect missing or weak data authenticity verification.

A.5.15 Access control partial match
prevents

Access-control rules can limit which upstream identities may cause the product to act on their behalf, reducing confused-deputy risk.

A.5.16 Identity management partial match
prevents

Proper identity management ensures the original requester identity is preserved and validated before the product forwards requests.

A.5.18 Access rights partial match
degrades

Explicit access-rights assignment can restrict the product’s ability to act as an unintended proxy for external actors.

A.8.2 Privileged access rights partial match
degrades

Privileged-access controls limit the rights the product may exercise on behalf of upstream callers, mitigating confused-deputy abuse.

A.8.20 Networks security partial match
mitigates

Network controls can enforce authenticated channels, reducing risk of accepting unauthentic data.

Hardening callouts derived

Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).

Oracle Linux 8 (2 rules)
  • V-248574 YUM must be configured to prevent the installation of patches, service packs, device drivers, or OL 8 system components that have not been digitally signed using a certificate that is recognized and approved by the organization. prevents CWE-345
  • V-248575 OL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
Oracle Linux 9 (1 rule)
  • V-271525 OL 9 must have GPG signature verification enabled for all software repositories. prevents CWE-345
RHEL 7 (2 rules)
  • V-204447 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
  • V-204448 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
RHEL 8 (2 rules)
  • V-230264 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
  • V-230265 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-345
RHEL 9 (1 rule)
  • V-257822 RHEL 9 must have GPG signature verification enabled for all software repositories. prevents CWE-345

References