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CVE-2026-46378

Dasel: Denial of service in dasel selector lexer due to infinite loop on unterminated regex literal

6.2 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.16%Up 0.1 points since Jun 12, 2026
90%50%10%1%

What each source reports

CVE List Score used 6.2

Dasel: Denial of service in dasel selector lexer due to infinite loop on unterminated regex literal

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.

Record
CVE-2026-46378
CVSS 3.1
6.2 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-835
Updated
2026-11-02
EUVDEUVD-2026-44994 6.2

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.

Record
EUVD-2026-44994
CVSS 3.1
6.2 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
GitHub AdvisoriesGHSA-m6xr-fvfg-5g64 7.5

Dasel: Denial of service in dasel selector lexer due to infinite loop on unterminated regex literal

Summary

dasel's selector lexer enters a non-terminating loop when tokenizing an unterminated regex pattern such as r/abc. A 2-byte input (r/) is sufficient to cause the tokenizer to consume 100% CPU on one core indefinitely.

I confirmed the issue on v3.3.1 (fba653c7f248aff10f2b89fca93929b64707dfc8) and on master commit 0dd6132e0c58edbd9b1a5f7ffd00dfab1e6085ad. I also verified the same code path is present in v3.0.0 (648f83baf070d9e00db8ff312febef857ec090a3). No fix is available yet.

Details

The bug is in the matchRegexPattern closure within (*Tokenizer).parseCurRune in selector/lexer/tokenize.go#L237-L247:

matchRegexPattern := func(pos int) *Token {
    if p.src[pos] != 'r' || !p.peekRuneEqual(pos+1, '/') {
        return nil
    }
    start := pos
    pos += 2
    for !p.peekRuneEqual(pos, '/') {  // line 243
        pos++
    }
    pos++
    return ptr.To(NewToken(RegexPattern, p.src[start+2:pos-1], start, pos-start))
}

When no closing / exists, peekRuneEqual returns false when pos >= srcLen (because the bounds check at line 40 returns false for out-of-range positions). Since !false = true, the loop condition remains true and pos increments indefinitely. The function never returns.

Notably, the same function already handles unterminated quoted strings by returning UnexpectedEOFError, but the regex pattern path does not perform a similar end-of-input check.

Minimal trigger: r/ (2 bytes)

Test environment:

  • MacBook Air (Apple M2), macOS / Darwin arm64
  • Go 1.26.1
  • dasel v3.3.1 (fba653c7f248aff10f2b89fca93929b64707dfc8)

PoC

package main

import (
	"fmt"
	"runtime"
	"time"

	"github.com/tomwright/dasel/v3/selector/lexer"
)

func main() {
	fmt.Printf("Go version: %s\n", runtime.Version())
	fmt.Printf("GOARCH: %s\n", runtime.GOARCH)
	fmt.Println()

	for _, input := range []string{"r/unterminated", "r/"} {
		fmt.Printf("Input: %s\n", input)
		done := make(chan string, 1)
		go func() {
			t := lexer.NewTokenizer(input)
			start := time.Now()
			tokens, err := t.Tokenize()
			elapsed := time.Since(start)
			if err != nil {
				done <- fmt.Sprintf("Error after %v: %v", elapsed, err)
			} else {
				done <- fmt.Sprintf("OK after %v: %d tokens", elapsed, len(tokens))
			}
		}()

		select {
		case result := <-done:
			fmt.Println(result)
		case <-time.After(5 * time.Second):
			fmt.Println("CONFIRMED: did not complete within 5s; tokenizer is stuck in non-terminating loop")
		}
		fmt.Println()
	}
}

Observed output on v3.3.1 in the test environment above:

Go version: go1.26.1
GOARCH: arm64

Input: r/unterminated
CONFIRMED: did not complete within 5s; tokenizer is stuck in non-terminating loop

Input: r/
CONFIRMED: did not complete within 5s; tokenizer is stuck in non-terminating loop

Impact

An attacker who can control or influence the selector/query string passed to dasel can cause the tokenizer to enter a non-terminating loop. The affected process consumes 100% CPU on one core and does not make progress until externally terminated.

The selector string is typically provided by the application developer, but there are deployment scenarios where it may be attacker-influenced:

  • Web applications using dasel for dynamic data querying
  • Applications that construct selectors from user input
  • Shared tooling environments where selectors are passed as parameters

Suggested Fix

The regex scanner should bounds-check and return an error on unterminated regex literals, consistent with unterminated quoted strings. Since matchRegexPattern currently returns *Token, the fix also requires changing the function signature to propagate errors. For example:

matchRegexPattern := func(pos int)…
Record
GHSA-m6xr-fvfg-5g64
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-835
Updated
2026-11-02
NVD 6.2

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.

Record
CVE-2026-46378
CVSS 3.1
6.2 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-835
Updated
2026-11-02
OSV 6.2

Dasel: Denial of service in dasel selector lexer due to infinite loop on unterminated regex literal

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.

Record
CVE-2026-46378
CVSS 3.1
6.2 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-835
Updated
2026-11-02
OSVDEBIAN-CVE-2026-46378 6.2

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.

Record
DEBIAN-CVE-2026-46378
CVSS 3.1
6.2 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
Show 4 moreShow less
OSVGHSA-m6xr-fvfg-5g64 7.5

Dasel: Denial of service in dasel selector lexer due to infinite loop on unterminated regex literal

Summary

dasel's selector lexer enters a non-terminating loop when tokenizing an unterminated regex pattern such as r/abc. A 2-byte input (r/) is sufficient to cause the tokenizer to consume 100% CPU on one core indefinitely.

I confirmed the issue on v3.3.1 (fba653c7f248aff10f2b89fca93929b64707dfc8) and on master commit 0dd6132e0c58edbd9b1a5f7ffd00dfab1e6085ad. I also verified the same code path is present in v3.0.0 (648f83baf070d9e00db8ff312febef857ec090a3). No fix is available yet.

Details

The bug is in the matchRegexPattern closure within (*Tokenizer).parseCurRune in selector/lexer/tokenize.go#L237-L247:

matchRegexPattern := func(pos int) *Token {
    if p.src[pos] != 'r' || !p.peekRuneEqual(pos+1, '/') {
        return nil
    }
    start := pos
    pos += 2
    for !p.peekRuneEqual(pos, '/') {  // line 243
        pos++
    }
    pos++
    return ptr.To(NewToken(RegexPattern, p.src[start+2:pos-1], start, pos-start))
}

When no closing / exists, peekRuneEqual returns false when pos >= srcLen (because the bounds check at line 40 returns false for out-of-range positions). Since !false = true, the loop condition remains true and pos increments indefinitely. The function never returns.

Notably, the same function already handles unterminated quoted strings by returning UnexpectedEOFError, but the regex pattern path does not perform a similar end-of-input check.

Minimal trigger: r/ (2 bytes)

Test environment:

  • MacBook Air (Apple M2), macOS / Darwin arm64
  • Go 1.26.1
  • dasel v3.3.1 (fba653c7f248aff10f2b89fca93929b64707dfc8)

PoC

package main

import (
	"fmt"
	"runtime"
	"time"

	"github.com/tomwright/dasel/v3/selector/lexer"
)

func main() {
	fmt.Printf("Go version: %s\n", runtime.Version())
	fmt.Printf("GOARCH: %s\n", runtime.GOARCH)
	fmt.Println()

	for _, input := range []string{"r/unterminated", "r/"} {
		fmt.Printf("Input: %s\n", input)
		done := make(chan string, 1)
		go func() {
			t := lexer.NewTokenizer(input)
			start := time.Now()
			tokens, err := t.Tokenize()
			elapsed := time.Since(start)
			if err != nil {
				done <- fmt.Sprintf("Error after %v: %v", elapsed, err)
			} else {
				done <- fmt.Sprintf("OK after %v: %d tokens", elapsed, len(tokens))
			}
		}()

		select {
		case result := <-done:
			fmt.Println(result)
		case <-time.After(5 * time.Second):
			fmt.Println("CONFIRMED: did not complete within 5s; tokenizer is stuck in non-terminating loop")
		}
		fmt.Println()
	}
}

Observed output on v3.3.1 in the test environment above:

Go version: go1.26.1
GOARCH: arm64

Input: r/unterminated
CONFIRMED: did not complete within 5s; tokenizer is stuck in non-terminating loop

Input: r/
CONFIRMED: did not complete within 5s; tokenizer is stuck in non-terminating loop

Impact

An attacker who can control or influence the selector/query string passed to dasel can cause the tokenizer to enter a non-terminating loop. The affected process consumes 100% CPU on one core and does not make progress until externally terminated.

The selector string is typically provided by the application developer, but there are deployment scenarios where it may be attacker-influenced:

  • Web applications using dasel for dynamic data querying
  • Applications that construct selectors from user input
  • Shared tooling environments where selectors are passed as parameters

Suggested Fix

The regex scanner should bounds-check and return an error on unterminated regex literals, consistent with unterminated quoted strings. Since matchRegexPattern currently returns *Token, the fix also requires changing the function signature to propagate errors. For example:

matchRegexPattern := func(pos int)…
Record
GHSA-m6xr-fvfg-5g64
CVSS 3.1
7.5 HighCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Weakness
CWE-835
Updated
2026-11-02
OSVUBUNTU-CVE-2026-46378 6.2

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.

Record
UBUNTU-CVE-2026-46378
CVSS 3.1
6.2 MediumCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Updated
2026-11-02
OSVGO-2026-5493 No score

Dasel: Denial of service in dasel selector lexer due to infinite loop on unterminated regex literal in github.com/tomwright/dasel

Dasel: Denial of service in dasel selector lexer due to infinite loop on unterminated regex literal in github.com/tomwright/dasel

Record
GO-2026-5493
Updated
2026-11-02
OSVopenSUSE-SU-2026:21483-1 No score

Security update for govulncheck-vulndb

This update for govulncheck-vulndb fixes the following issues:

  • Update to version 0.0.20260723T184607 2026-07-23T18:46:07Z (jsc#PED-11136).

Go CVE Numbering Authority IDs added or updated with aliases:

  • GO-2026-4730 CVE-2026-33022 GHSA-cv4x-93xx-wgfj
  • GO-2026-4761 CVE-2026-33211 GHSA-j5q5-j9gm-2w5c
  • GO-2026-5102 CVE-2026-45021 GHSA-3vcp-chfh-f6r2
  • GO-2026-5272 CVE-2026-40938 GHSA-94jr-7pqp-xhcq
  • GO-2026-5486 CVE-2026-40924 GHSA-m2cx-gpqf-qf74
  • GO-2026-5542 CVE-2026-40090 GHSA-pj97-4p9w-gx3q
  • GO-2026-5630 CVE-2026-25542 GHSA-rmx9-2pp3-xhcr
  • GO-2026-5643 CVE-2026-40923 GHSA-rx35-6rhx-7858
  • GO-2026-5675 CVE-2026-41492 GHSA-vvf7-6rmr-m29q
  • GO-2026-5711 CVE-2026-40161 GHSA-wjxp-xrpv-xpff
  • GO-2026-5746 CVE-2026-41567 GHSA-x86f-5xw2-fm2r
  • GO-2026-5749 CVE-2026-41328 GHSA-x92x-px7w-4gx4
  • GO-2026-5837 CVE-2026-44840 GHSA-q2m9-6jp9-c6mc
  • GO-2026-5929 CVE-2026-44342 GHSA-26v7-h57m-gh9m
  • GO-2026-5930 CVE-2026-33655 GHSA-6qcr-qxgr-m7fv
  • GO-2026-5933 GHSA-3g4q-2f67-2gvh
  • GO-2026-5934 GHSA-59qp-cfj3-rp64
  • GO-2026-5935 GHSA-7856-g3gv-9wq8
  • GO-2026-5936 CVE-2026-53552 GHSA-26rh-24rg-j3vv
  • GO-2026-5937 CVE-2026-53508 GHSA-2jcc-mxv7-p3f9
  • GO-2026-5938 CVE-2026-53553 GHSA-4g5x-hcwm-82jw
  • GO-2026-5939 CVE-2026-10517 GHSA-698x-9w2p-7vvp
  • GO-2026-5940 CVE-2026-53572 GHSA-6w3m-4hhp-775q
  • GO-2026-5941 CVE-2026-53487 GHSA-gvhc-wv3v-7pf8
  • GO-2026-5942 CVE-2026-46600
  • GO-2026-5944 CVE-2026-50197 GHSA-659f-rgp5-w4wf
  • GO-2026-5945 CVE-2026-6815 GHSA-rmxx-v9rj-vpvg
  • GO-2026-5946 CVE-2026-52831 GHSA-v5px-423j-pf7p
  • GO-2026-5947 CVE-2026-53649 GHSA-xqhv-chqm-fhcc
  • GO-2026-5948 CVE-2026-50554 GHSA-588f-fvcv-xhvf
  • GO-2026-5949 CVE-2026-50553 GHSA-rqrh-8wpv-x7hh
  • GO-2026-5950 CVE-2026-53602 GHSA-339v-266x-79xr
  • GO-2026-5951 CVE-2026-10219 GHSA-6jm8-4fhr-5w64
  • GO-2026-5952 CVE-2026-49834 GHSA-9vcr-p3rj-q5q6
  • GO-2026-5953 CVE-2026-9094 GHSA-c9w5-qp6m-m395
  • GO-2026-5956 CVE-2026-55252 GHSA-h5g6-xmh4-hc37
  • GO-2026-5957 CVE-2026-54158 GHSA-5xfx-xj4h-5p7r
  • GO-2026-5958 CVE-2026-54068 GHSA-gcm7-57gf-953c
  • GO-2026-5959 CVE-2026-54072 GHSA-h29v-hj44-q8cv
  • GO-2026-5961 CVE-2026-54069 GHSA-hvr9-72v2-fff3
  • GO-2026-5962 CVE-2026-54088 GHSA-m93h-4hw7-5qcm
  • GO-2026-5963 CVE-2026-54067 GHSA-mvjr-vv3c-w4qv
  • GO-2026-5964 CVE-2026-54066 GHSA-p4m3-mgmm-c664
  • GO-2026-5965 CVE-2026-54070 GHSA-w7cg-whh7-xp28
  • GO-2026-5966 CVE-2026-54089 GHSA-xqp3-jq6g-x3qm
  • GO-2026-5967 CVE-2026-50551 GHSA-56mp-4f3v-fgj2
  • GO-2026-5968 CVE-2026-54174 GHSA-fpg8-7664-jc5q
  • GO-2026-5969 GHSA-g936-7jqj-mwv8
  • GO-2026-5970 CVE-2026-56852
  • GO-2026-5973 CVE-2026-54250 GHSA-jxr7-mqhw-9p98
  • GO-2026-5974 CVE-2026-44300 GHSA-wmj8-9953-vff5
  • GO-2026-5975 CVE-2026-50018 GHSA-42j2-w334-qxw7
  • GO-2026-5976 CVE-2026-50141 GHSA-g7mm-9vx7-jm7h
  • GO-2026-5977 CVE-2026-50013 GHSA-qrh4-p6v4-mrfg
  • GO-2026-5978 CVE-2026-50125 GHSA-qw5r-ppcg-f8rj
  • GO-2026-5979 CVE-2026-50006 GHSA-xrcf-6jh3-ggvx
  • GO-2026-5980 CVE-2026-50158 GHSA-2c7f-fxww-6w6c
  • GO-2026-5981 GHSA-mqxv-9rm6-w8qc
  • GO-2026-5982 GHSA-pqg7-v6wh-3pfp
  • GO-2026-5984 CVE-2026-53604 GHSA-2p2f-px33-4vv5
  • GO-2026-5985 GHSA-7rx3-5wx3-5v76
  • GO-2026-5986 CVE-2026-61699 GHSA-cm26-5974-52h8
  • GO-2026-5987 CVE-2026-55513 GHSA-g4x6-jcvr-9m3g
  • GO-2026-5988 CVE-2026-54628 GHSA-hwrq-8wxh-q4xv
  • GO-2026-5989 CVE-2026-55512 GHSA-m3cx-mwpg-32jg
  • GO-2026-5990 CVE-2026-54629 GHSA-mf78-3rpf-r784
  • GO-2026-5991 CVE-2026-53603 GHSA-q4vm-pq3q-8wgq
  • GO-2026-5992 CVE-2026-61549 GHSA-qf34-295c-26v8
  • GO-2026-5996 CVE-2026-54450 GHSA-pph6-vfjv-vpjw
  • GO-2026-5997 CVE-2026-54452 GHSA-xgch-x3mx-cm3c
  • GO-2026-5998 CVE-2026-54495 GHSA-398h-7f66-3h4p
  • GO-2026-5999 CVE-2026-10814 GHSA-jh6h-v6mp-h22v
  • GO-2026-6002 CVE-2026-58196 GHSA-pr64-jmmf-jp54
  • GO-2026-6003 CVE-2026-53714 GHSA-22xc-xg2r-9j7v
  • GO-2026-6004 CVE-2026-52833 GHSA-3v79-m2cg-89ww
  • GO-2026-6005 CVE-2026-53715 GHSA-8fv2-88gg-hm7q
  • GO-2026-6006 CVE-2026-53716 GHSA-cxpq-8v7q-cg56 *…
Record
openSUSE-SU-2026:21483-1
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
github.com/tomwright/dasel/v3
Go
 3.0.0 up to 3.10.1
3.10.1
dasel
Debian:14
 before 3.11.0-1, plus listed versions
2.8.1-13.8.0-13.8.1-1
3.11.0-1
github.com/tomwright/dasel
Go
 All versions None known
github.com/tomwright/dasel/v2
Go
 All versions None known
dasel
Ubuntu:Pro:24.04:LTS
 All versions, plus listed versions
2.6.0-12.6.0-1build12.6.0-1ubuntu0.12.6.0-1ubuntu0.22.6.0-1ubuntu0.2+esm12.6.0-1ubuntu0.32.6.0-1ubuntu0.3+esm12.6.0-1ubuntu0.3+esm2
 None known
dasel
Ubuntu:26.10
 All versions, plus listed versions
2.8.1-1build13.11.0-13.11.2-13.11.2-2
 None known
dasel
Ubuntu:26.04:LTS
 All versions, plus listed versions
2.8.1-12.8.1-1build1
 None known
govulncheck-vulndb
openSUSE:Leap 16.0
From an advisory covering 1734 CVEs
 before 0.0.20260723T184607-160000.1.1
0.0.20260723T184607-160000.1.1

History

History
RecordedChangedSources
affected, facts
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-46378 is a medium vulnerability (CVSS 6.2) in Tomwright Dasel, published May 19, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.16%, the 5th percentile. Fixed in github.com/tomwright/dasel/v3 3.10.1.

References

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Left out here: 1,543 references and the rest of 3 source descriptions. The JSON record has them.

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