CVE-2026-109841
Description
A flaw was found in undici. The HTTP client improperly handles case sensitivity when verifying Subresource Integrity (SRI) algorithm tokens. When an application specifies an uppercase or mixed-case algorithm name, undici treats the token as unrecognized and skips verification instead of enforcing it. A remote attacker who controls the HTTP response body can exploit this flaw to deliver modified content without triggering an integrity error, bypassing intended security protections.
Statement
In Red Hat environments, this vulnerability is rated as Moderate impact because successful exploitation requires an adversary capable of tampering with network responses alongside the uncommon prerequisite that an application explicitly configured non-lowercase hashing algorithms for Subresource Integrity checks. Standard deployments typically employ lowercase digest names, which properly enforce validation and prevent bypass. Furthermore, the issue is constrained to compromising response integrity when client workloads rely on undici's fetch implementation under these specific naming conditions, without directly leading to system compromise or arbitrary code execution.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.9 | 7.5 | 5.9 |
| Attack Vector | Network | Network | Network |
| Attack Complexity | High | Low | High |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Unchanged | Unchanged | Unchanged |
| Confidentiality | None | None | None |
| Integrity Impact | High | High | High |
| Availability Impact | None | None | None |
Vector
Red Hat: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
cve.org: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N
Understanding the Weakness (CWE)
Integrity,Other
Technical Impact: Modify Application Data; Other
Integrity checks usually use a secret key that helps authenticate the data origin. Skipping integrity checking generally opens up the possibility that new data from an invalid source can be injected.
Integrity,Other
Technical Impact: Other
Data that is parsed and used may be corrupted.
Non-Repudiation,Other
Technical Impact: Hide Activities; Other
Without a checksum check, it is impossible to determine if any changes have been made to the data after it was sent.
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