CVE Watchtower

CVE-2026-123370compose-lint >= 0.9.0,

NVD

Vulnerability Summary

### Impact

`compose-lint fix --apply` converts the line numbers its fixers work with into positions in the file. The YAML parser treats a lone carriage return, U+0085, U+2028 and U+2029 as line breaks, but the conversion counted only `\n`. One of those characters inside a quoted value, which most editors and diff views don't show, shifted every later edit down by one line.

A Compose file from a pull request can use this to make a fix delete the line after the one it meant to change. For example, fixing CL-0014 (`logging: driver: none`) instead removes `driver: none` and the following `networks: [internal]`, moving the service off an internal-only network onto the default bridge. The result is still valid Compose, every check `fix` runs after editing passes, and the command reports `applied 1 fix(es)` and exits 0. A later `compose-lint check` passes too, because no rule requires `networks:`. The dry-run diff (without `--apply`) does show the removed lines, but `--apply` prints only the note for the fix that was selected.

A related crash on the same files could empty the SARIF output for every file in the run. GitHub Code Scanning rejects an empty SARIF upload, which fails the step, so that part does not report a false clean result there.

Found during an internal pre-1.0 security review.

**Docker image.** `composelint/compose-lint` tags 0.9.0 through 0.17.0, and the matching minor tags, are affected when used to run `fix --apply`. Fixed from `0.18.0`.

The GitHub Action does not run `fix` and is not affected.

### Patches

Fixed in 0.18.0. Line splitting and position conversion now share one definition of a line break, so they can't disagree. A Compose file containing an ambiguous line break (a lone `\r`, U+0085, U+2028 or U+2029) is refused with exit code 2, because no line numbering is correct for both the parser and the editor. CRLF and LF files are unaffected.

### Workarounds

- Upgrade to 0.18.0 or later.
- On older versions, review the dry-run diff before `--apply`, and don't run `fix --apply` over files from untrusted pull requests.

### Reproduction

```yaml
services:
web:
image: nginx@sha256:<digest>
labels:
note: "line one<U+2028>line two"
logging:
driver: none
networks: [internal]
networks:
internal:
internal: true
```

`compose-lint fix --apply compose.yml` on 0.17.0 reports `applied 1 fix(es)`, exits 0, and removes both `driver: none` and `networks: [internal]`.
Severity Level
MEDIUM
Published Date
Nov 9, 2026
Last Modified
Nov 10, 2026
Exploitation Status
No confirmed exploitation yet
CVE Record Status
Published
EPSS Score (30-Day)
0.33%Probability
Root Weakness (CWE)
See the MITRE CWE entry for the full definition of this weakness.
CVSS v4.0 Base Metrics — Score 5.1
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:L/VA:N/SC:N/SI:L/SA:N
Attack VectorNetwork
Attack ComplexityLow
Attack RequirementsNone
Privileges RequiredNone
User InteractionActive
Confidentiality (Vulnerable System)None
Integrity (Vulnerable System)Low
Availability (Vulnerable System)None
Confidentiality (Subsequent System)None
Integrity (Subsequent System)Low
Availability (Subsequent System)None

Affected & Patched Versions

Affected Versions
  • compose-lint >= 0.9.0, <= 0.17.0
Patched Versions
No patched version published yet
Until a fix ships, reduce exposure:
  • Restrict access to the affected service or interface to trusted networks.
  • Disable the affected feature if you do not need it.
  • Watch the vendor advisory for a firmware or software update.

What to do

Fix it during your normal patch cycle. No exploitation is confirmed yet.

  1. Check whether you run compose-lint >= 0.9.0, and which version.
  2. No patched version is listed yet. Limit access to the affected service to trusted networks, and disable the feature if you can.
  3. Subscribe to the vendor advisory so you learn when a fix ships.

Timeline

  • Nov 9, 2026Published
  • Nov 10, 2026Record last modified

Score, severity and exploitation changes are tracked from the day Watchtower started logging them.

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Data last checked: Nov 10, 2026 17:00 UTC