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NVD / CVE Program· CNA GitHub_M

CVE-2023-49284: Command substitution output can trigger shell expansion in fish shell

Noroxi assessment

Priority: Monitor (action score 26/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.47% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. A user must open a link or visit a page. No special conditions are required; it is repeatable.
  • Fixed version: fish (Debian:12) 3.6.0-3.1+deb12u1; fish (Debian:13) 3.6.4-1; fish (openSUSE:Leap 15.4) 3.3.1-bp154.3.3.1.
  • Severity is disputed: the assigning authority (CNA) scores it 3.9, NVD 6.6.

Low priority for now. Upgrade to fish (Debian:12) 3.6.0-3.1+deb12u1; fish (Debian:13) 3.6.4-1; fish (openSUSE:Leap 15.4) 3.3.1-bp154.3.3.1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

fish is a smart and user-friendly command line shell for macOS, Linux, and the rest of the family. fish shell uses certain Unicode non-characters internally for marking wildcards and expansions. It will incorrectly allow these markers to be read on command substitution output, rather than transforming them into a safe internal representation. While this may cause unexpected behavior with direct input (for example, echo \UFDD2HOME has the same output as echo $HOME), this may become a minor security problem if the output is being fed from an external program into a command substitution where this output may not be expected. This design flaw was introduced in very early versions of fish, predating the version control system, and is thought to be present in every version of fish released in the last 15 years or more, although with different characters. Code execution does not appear to be possible, but denial of service (through large brace expansion) or information disclosure (such as variable expansion) is potentially possible under certain circumstances. fish shell 3.6.2 has been released to correct this issue. Users are advised to upgrade. There are no known workarounds for this vulnerability.

MediumCVSS 6.6 · v3.1—No exploit Fix available
Published
Dec 4, 2023
Updated
Jun 17, 2026
EPSS
0.4% · 41th percentile

Report tools

JSON

Action score

26

Monitor

Low priority for now.

CVSS
26 / 40 · 6.6 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CNA vs NVD score

NVD
6.6
CNA · GitHub_M
3.9
2.7 point gap

CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:L/I:N/A:L

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Follow CVE-2023-49284

When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

VendorProduct
fishshellfish

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • fishshell fishbefore 3.6.2

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

  • fish-shell fish-shell

    • < 3.6.2affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12fishbefore 3.6.0-3.1+deb12u13.6.0-3.1+deb12u1
Debian:13fishbefore 3.6.4-13.6.4-1
openSUSE:Leap 15.4fishbefore 3.3.1-bp154.3.3.13.3.1-bp154.3.3.1
openSUSE:Leap 15.5fishbefore 3.3.1-bp155.4.3.13.3.1-bp155.4.3.1
openSUSE:Tumbleweedfishbefore 3.6.4-1.13.6.4-1.1
SUSE:Package Hub 15 SP4fishbefore 3.3.1-bp154.3.3.13.3.1-bp154.3.3.1
SUSE:Package Hub 15 SP5fishbefore 3.3.1-bp155.4.3.13.3.1-bp155.4.3.1

Same product

fishshell: all records

Other highest-scoring records for the same primary product.

  • CVE-2014-2914fish (aka fish-shell) 2.0.0 before 2.1.1 does not restrict access to the configuration service (aka fish_config), which allows remote attack
    40Plan
  • CVE-2022-20001fish is a command line shell.
    31Monitor
  • CVE-2014-3219fish before 2.1.1 allows local users to write to arbitrary files via a symlink attack on (1) /tmp/fishd.log.%s, (2) /tmp/.pac-cache.$USER, (
    31Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2014-2905May 2, 2014 · fish (aka fish-shell) 1.16.0 before 2.1.1 does not properly check the credentials, which allows local users to gain privileges via the unive
    27Monitor
  • ← EarlierCVE-2014-2906Jan 28, 2020 · The psub function in fish (aka fish-shell) 1.16.0 before 2.1.1 does not properly create temporary files, which allows local users to execute
    28Monitor
  • ← EarlierCVE-2014-3856Jan 28, 2020 · The funced function in fish (aka fish-shell) 1.23.0 before 2.1.1 does not properly create temporary files, which allows local users to gain
    28Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
debian:fish3.6.0-3.1+deb12u1 · Debian:12Package registry (OSV)
opensuse:fish3.3.1-bp154.3.3.1 · openSUSE:Leap 15.4Package registry (OSV)
suse:fish3.3.1-bp154.3.3.1 · SUSE:Package Hub 15 SP4Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • A user must open a link or visit a page.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
Required
Scope
Unchanged
Confidentiality impact
High
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-436 · Interpretation Conflict

CVSS vector

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

nvd-primary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

ATT&CK techniques

—

Change log

  1. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (1 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records