CVE-2026-14650: Denial-of-Service in connorskees grass Sass Compiler

Technical summary

CVE-2026-14650 affects the grass_compiler::raw_to_parse_error function in the UTF-8 Character Handler component. The vulnerability allows local attackers with limited privileges to trigger a denial-of-service condition by manipulating input that causes extended compilation time or resource exhaustion. The issue is classified under CWE-404 (Improper Resource Validation). The project maintainer has contextualized this within the broader Sass compiler ecosystem, noting that compile-time complexity is not necessarily linear to input size and that algorithms like @extend are inherently exponential—characteristics that vendors and users must manage through architectural decisions and resource limits rather than treating as security defects.

Business impact

For organizations using grass as a build-time tool, this vulnerability presents minimal business risk due to its local-execution-only requirement and the low CVSS score of 3.3. The primary concern would be developer experience disruption if an attacker with system access submits malicious Sass code during the build pipeline. Organizations that run untrusted Sass compilation or use grass in a multi-tenant build environment should be more cautious. Most standard single-developer or CI/CD environments where grass processes trusted stylesheets will see negligible impact.

Affected systems

connorskees grass versions up to and including 0.13.4 are affected. The vulnerability requires local system access to exploit, meaning it is primarily a concern for shared development machines, multi-user build systems, or environments where untrusted users can submit Sass code for compilation. Desktop developers and isolated CI/CD runners with properly secured access controls are at lower risk.

Exploitability

Exploitation is straightforward from a technical standpoint—a local attacker can craft malicious Sass input that triggers exponential compilation behavior. However, real-world exploitability is constrained by the local-execution requirement (CVSS vector: AV:L) and the need for unprivileged user access (PR:L). The published exploit demonstrates the concept but does not enable remote attacks or privilege escalation. The technique likely mirrors known patterns in Sass compilation (recursive functions, nested mixins, or @extend chains) that are already well understood by the development community.

Remediation

Update connorskees grass to a version newer than 0.13.4. Verify the specific patched version against the upstream project repository and release notes. As an interim measure, organizations can mitigate risk by restricting who can submit Sass code for compilation, running the compiler in isolated environments with resource limits (CPU and memory caps), and using timeout mechanisms in build pipelines. Consider validating input Sass complexity before compilation in high-risk scenarios.

Patch guidance

Check the connorskees grass GitHub repository for releases following 0.13.4 and verify that the fix addresses the UTF-8 character handler function. Apply updates through your package manager (e.g., npm, cargo, etc., depending on how grass is distributed). Test the patched version in a staging environment to ensure build pipeline compatibility before production deployment. Organizations on version 0.13.4 or earlier should prioritize this update in their next maintenance window, though it is not critical for standard use cases.

Detection guidance

Monitor build logs for unusual compilation timeouts or resource spikes when processing Sass files. If grass is running in a CI/CD environment, set resource limits (CPU, memory, time) to detect and halt runaway compilations. Review Sass files for suspicious patterns such as deeply nested mixins, large @extend rule sets, or recursive function definitions that could be intentionally crafted to trigger the vulnerability. For forensic purposes, capture compilation times and resource metrics as a baseline to identify anomalies.

Why prioritize this

This vulnerability rates as low priority for most organizations due to its local-execution-only attack vector, low CVSS score (3.3), and alignment with expected compiler behavior. Prioritization should be elevated only for multi-tenant build systems, shared development environments, or scenarios where untrusted Sass code is regularly compiled. Standard development teams and secured CI/CD pipelines can address this during routine patch cycles rather than emergency maintenance.

Risk score, explained

The CVSS 3.1 score of 3.3 (LOW) reflects the combination of local-only attack vector (AV:L), low privilege requirements (PR:L), and limited impact scope (A:L—availability only, no confidentiality or integrity compromise). The score appropriately de-emphasizes this issue because the denial-of-service condition does not propagate to dependent systems and can be mitigated through standard resource controls. The vulnerability is not remotely exploitable and does not grant elevated privileges.

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