CVE-2026-35391
Bulwarkmail Webmail ≤ 1.4.11
Raw vector
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/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:XSummary
CVE-2026-35391 is a high-severity Use of Less Trusted Source (CWE-348) vulnerability in Bulwarkmail Webmail. Its CVSS base score is 8.7 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Path Interception (T1034); ranked at the 3th 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-4 (Information Flow Enforcement) and IA-3 (Device Identification and Authentication) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-35391 affects Bulwark Webmail, a self-hosted webmail client for Stalwart Mail Server, in versions prior to 1.4.11. The vulnerability resides in the getClientIP() function within lib/admin/session.ts, which naively trusts the first (leftmost) entry of the X-Forwarded-For HTTP header—a value fully controlled by the client. This flaw, classified under CWE-348 (Use of Less Trusted Source), enables IP address spoofing and carries a CVSS v3.1 base score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N), indicating high integrity impact with no confidentiality or availability effects.
Remote attackers require no privileges or user interaction to exploit this over the network with low complexity. By forging the X-Forwarded-For header, they can spoof their source IP address to evade IP-based rate limiting, facilitating brute-force attacks against the admin login interface. Additionally, attackers can manipulate audit log entries to make malicious activities appear to originate from arbitrary IP addresses, potentially complicating incident response and attribution.
The GitHub Security Advisory (GHSA-7pj2-232x-6698) confirms the issue is resolved in Bulwark Webmail version 1.4.11, which presumably implements proper IP extraction logic that does not rely on client-controlled headers. Security practitioners should upgrade to 1.4.11 or later and review proxy configurations to ensure trusted proxies correctly forward real client IPs while validating or stripping untrusted X-Forwarded-For values.
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-19480
Vulnerability Data
Bulwark Webmail is a self-hosted webmail client for Stalwart Mail Server. Prior to 1.4.11, the getClientIP() function in lib/admin/session.ts trusted the first (leftmost) entry of the X-Forwarded-For header, which is fully controlled by the client. An attacker could forge their…
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source IP address to bypass IP-based rate limiting (enabling brute-force attacks against the admin login) or forge audit log entries (making malicious activity appear to originate from arbitrary IP addresses). This vulnerability is fixed in 1.4.11.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 7 hardening rules · 4 OS baselines
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Mitigating Controls (NIST 800-53 r5) AI
Provenance tracking supplies the information needed to distinguish and prefer more-trusted sources, reducing the chance that a weaker source is chosen.
Information flow enforcement can require that data or decisions are taken only from explicitly approved, higher-trust sources rather than less-verified ones.
Device identification and authentication forces verification of the source before any data it supplies is used, eliminating reliance on unauthenticated inputs.
Boundary protection monitors and filters traffic at external interfaces, structurally limiting the ability to accept data from less-trusted external sources.
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.
Explicit authenticity/integrity checks before use directly reduce selection of a less-trusted source.
Correlating multiple sources can surface discrepancies that discourage reliance on the less-trusted one.
Protecting data-in-transit integrity helps ensure the more-trusted source is the one whose data is accepted.
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.
Secure architecture principles include trusted input channels and source verification mechanisms.
Security testing can detect and prevent acceptance of data from less-trusted sources during development.
Network security controls can enforce trusted data paths and source validation, reducing reliance on unverified inputs.
Secure network services include source validation and integrity checks that help prevent acceptance of data from less-trusted origins.
Application security requirements can mandate trusted data sources and input validation, directly addressing the weakness.
Secure coding practices can enforce checks that prefer or validate the more trusted data source.
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 (1 rule)
- 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-348
Oracle Linux 9 (1 rule)
- V-271525 OL 9 must have GPG signature verification enabled for all software repositories. prevents CWE-348
RHEL 7 (1 rule)
- 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-348