Dasel: Selector lexer panics on trailing whitespace in parseCurRune

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.2 · CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-62866: 0.19% estimated exploitation activity in the next 30 days; percentile 8.98 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Same panic class as GHSA-m5j3-4634-c2vq and GHSA-m6xr-fvfg-5g64, sister site on the same function. Trigger is any selector ending in whitespace: dasel query 'a ' panics at selector/lexer/tokenize.go:60. The whitespace-skip loop right above (lines 55-57) advances p.i to p.srcLen when the input is all-whitespace or whitespace-trailing. The very next line reads p.src[p.i] without a bounds check. Vulnerable code selector/lexer/tokenize.go:53-74 (v3.11.0): Lines 69-71 right below already do the bounds check after the comment-skip path. The whitespace-only path slipped past it. Reproduce Other inputs that hit it: ' ', $'a\t', $'a\n', 'a ?? ', 'a + '. Any token (or no token) followed by whitespace. Reachable directly from the library too - dasel.Query(ctx, input, "a ") panics the same way. Project-style test reproducer that fails on current main: Impact Process crash, no auth, no preconditions. Same severity tier as the two May 13 advisories on this file. Affected versions All v3.x. The…

Published by the source

22 Sep 2026, 19:52 UTC

Last modified by the source

1 Oct 2026, 20:45 UTC

Source last checked

26 Oct 2026, 15:29 UTC

1. Revision 3 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-65gg-g7rw-6cpc

2. Revision 2 · amended · 24 Oct 2026

   Amended from osv record GO-2026-6548

3. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-65gg-g7rw-6cpc

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# Patch Next advisory brief: CVE-2026-62866

Advisory: Dasel: Selector lexer panics on trailing whitespace in `parseCurRune`
IDs: CVE-2026-62866, GHSA-65gg-g7rw-6cpc
Record: https://patchnext.com/advisories/cve-2026-62866 (revision 3, source checked 26 Oct 2026, 15:29 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Partial vendor fix; fixed versions by package: github.com/tomwright/dasel/v3 3.11.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- Go github.com/tomwright/dasel: affected every version
- Go github.com/tomwright/dasel/v2: affected every version
- Go github.com/tomwright/dasel/v3: affected >= 3.0.0, < 3.11.2; fixed in 3.11.2

## Suggested inspection (read-only)
- Go github.com/tomwright/dasel: check the installed version with your package manager.
- Go github.com/tomwright/dasel/v2: check the installed version with your package manager.
- Go github.com/tomwright/dasel/v3: check the installed version with your package manager.

## Supported action
No complete vendor fix is recorded. Follow the primary source's mitigation guidance and check this record again before closing anything.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on github.com/tomwright/dasel, github.com/tomwright/dasel/v2, github.com/tomwright/dasel/v3.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-65gg-g7rw-6cpc (OSV record GHSA-65gg-g7rw-6cpc lists affected ranges: Go github.com/tomwright/dasel/v3 >=3.0.0 <3.11.2 (fixed))
- Verified: https://osv.dev/vulnerability/GO-2026-6548 (OSV record GO-2026-6548 lists affected ranges: Go github.com/tomwright/dasel >=0; Go github.com/tomwright/dasel/v2 >=0; Go github.com/tomwright/dasel/v3 >=3.0.0 <3.11.2 (fixed))
- Verified: https://github.com/advisories/GHSA-65gg-g7rw-6cpc (GitHub-reviewed advisory GHSA-65gg-g7rw-6cpc lists affected ranges: Go github.com/tomwright/dasel/v3 >=3.0.0 <3.11.2)

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