# CVE-2026-46378: Dasel: Denial of service in dasel selector lexer due to infinite loop on unterminated regex literal

> An attacker can cause a denial of service via infinite loop in the selector lexer when processing unterminated regex literals in Dasel.

- **Severity:** Medium 6.2 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 16 Jul 2026
- **Updated:** 17 Jul 2026
- **Also known as:** DEBIAN-CVE-2026-46378, GHSA-m6xr-fvfg-5g64, GO-2026-5493, UBUNTU-CVE-2026-46378

## What is CVE-2026-46378?

CVE-2026-46378 is a medium-severity denial of service vulnerability in TomWright dasel, published on 16 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

Dasel is a command-line tool and library for querying, modifying, and transforming data structures. From 3.0.0 until 3.10.1, the selector lexer matchRegexPattern closure in (*Tokenizer).parseCurRune in selector/lexer/tokenize.go loops while tokenizing an unterminated regex literal such as r/ because peekRuneEqual returns false after the end of input, allowing attacker-controlled selector strings to consume CPU indefinitely. This issue is fixed in version 3.10.1.

Weakness: CWE-835 (Loop with Unreachable Exit Condition)

## Which versions are affected by CVE-2026-46378?

5 open source packages ship an affected version, including github.com/tomwright/dasel/v3, github.com/tomwright/dasel and github.com/tomwright/dasel/v2.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `github.com/tomwright/dasel/v3` | Go | From 3.0.0 | 3.10.1 |
| `github.com/tomwright/dasel/v3` | Go | From 3.0.0 | 3.10.1 |
| `github.com/tomwright/dasel/v3` | Go | From 3.0.0 | 3.10.1 |
| `github.com/tomwright/dasel` | Go | All versions | None |
| `github.com/tomwright/dasel/v2` | Go | All versions | None |

## How do I fix CVE-2026-46378?

Upgrade github.com/tomwright/dasel/v3 to 3.10.1 or later.

## Is CVE-2026-46378 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-46378 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-46378 and fix it if it is affected.

What it is: CVE-2026-46378 is a medium-severity denial of service vulnerability in TomWright dasel, published on 16 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-46378 exists.

Affected packages and fixed versions:
- github.com/tomwright/dasel/v3 (Go): affected from 3.0.0; fixed in 3.10.1
- github.com/tomwright/dasel/v3 (Go): affected from 3.0.0; fixed in 3.10.1
- github.com/tomwright/dasel/v3 (Go): affected from 3.0.0; fixed in 3.10.1
- github.com/tomwright/dasel (Go): affected all versions; no fix listed
- github.com/tomwright/dasel/v2 (Go): affected all versions; no fix listed

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-46378/ (Markdown: https://insights.sbomify.com/CVE-2026-46378/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-46378
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-46378
- OSV: https://osv.dev/vulnerability/CVE-2026-46378

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-46378/
Summaries are generated and may contain mistakes; the official description above is the record.