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NVD / CVE Program· CNA VulnCheck

CVE-2026-79661: Ech0 before 4.7.3 Unauthenticated fav_count Modification

Noroxi assessment

Priority: Monitor (action score 27/100)

  • 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: 0.43% (FIRST EPSS).
  • Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
  • According to CISA the attack is automatable: targets can be found by mass scanning.
  • Fixed version: lin-snow Ech0 4.7.3.

Low priority for now. Upgrade to lin-snow Ech0 4.7.3 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

Ech0 through 4.5.6 registers the PUT /api/echo/like/:id endpoint on the public router group without authentication or rate limiting. Unauthenticated attackers can increment the fav_count counter of any echo (including private echoes) by supplying its UUID, which can be harvested from the public GET /api/echo/page feed. Repeated requests are accepted without deduplication, each triggering a database write and a four-key cache invalidation, allowing attackers to inflate popularity metrics and amplify load on the database and cache. Fixed in 4.7.3.

MediumCVSS 6.9 · v4.0—No exploit Fix available
Published
Aug 25, 2026
Updated
Aug 31, 2026
EPSS
0.4% · 37th percentile

Report tools

JSON

Action score

27

Monitor

Low priority for now.

CVSS
27 / 40 · 6.9 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.4%

CISA SSVC decision

Exploitation
proof of concept
Automatable
yes
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · VulnCheck
6.9
NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N

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-2026-79661

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.

—

Versions reported by the vendor

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

  • lin-snow Ech0

    • 4.7.3not affected
    • before 4.7.3affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Gogithub.com/lin-snow/Ech0before 1.4.8-0.20260503035905-cecc2c19b5901.4.8-0.20260503035905-cecc2c19b590

Same product

lin-snow: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-79664Ech0 before 4.7.3 Access Token Revocation Bypass
    36Monitor
  • CVE-2026-79662Ech0 before 4.7.3 OAuth Redirect URI Validation Bypass
    35Monitor
  • CVE-2026-79673Ech0 before 4.4.3 Scope Bypass via profile:read Token
    34Monitor

Published before and after this one in the same product

  • ← EarlierCVE-2026-79658Aug 25, 2026 · Ech0 before 5.0.1 Denial of Service via Accept-Language
    34Monitor
  • ← EarlierCVE-2026-79660Aug 25, 2026 · Ech0 before 4.7.3 Email Disclosure via Public API
    27Monitor
  • Later →CVE-2026-79663Aug 25, 2026 · Ech0 before 4.7.3 Stored XSS via RSS feed tag names
    19Monitor

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
lin-snow Ech04.7.3Vendor (CNA)
Go:github.com/lin-snow/Ech01.4.8-0.20260503035905-cecc2c19b590Package 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.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

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

No commit or PR link among the references.

Credits

All researchers

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

Variant candidates

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

—

Chain candidates

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

  • CVE-2026-796590 days apartEch0 before 4.7.3 Server-Side Request Forgery via fetchPeerConnectInfo
    33Monitor
  • CVE-2026-796710 days apartEch0 before 4.4.3 SSRF via DNS Resolution Bypass
    20Monitor
  • CVE-2026-796700 days apartEch0 before 4.4.3 Stored XSS via SVG Upload
    19Monitor

Bug bounty scope

No known public program.

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

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
X

Weakness class (CWE)

CWE-770 · Allocation of Resources Without Limits or Throttling

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

Attack context

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

Change log

  1. Fix✗ → ✓

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References

Show all references (1 more)

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

All records