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Fencer Vulns
medium 6.5

CVE-2026-79661 json

Ech0 before 4.7.3 Unauthenticated fav_count Modification

published 2026-05-07 6 mo ago modified 2026-08-31 2 mo ago also GHSA-pj6q-4vq4-r8cg , GO-2026-5541 , EUVD-2026-65453

cvss
6.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.4%
EPSS 0.4% chance of exploitation in 30 days, percentile 37%
public exploits
0
none known

Summary

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.

Patch / fix

  • go github.com/lin-snow/Ech0 1.4.8-0.20260503035905-cecc2c19b590
  • go github.com/lin-snow/ech0 1.4.8-0.20260503035905-cecc2c19b590
  • lin-snow Ech0 4.7.3

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
2 mo ago

Exploit prediction

0.43% chance of exploitation in the next 30 days, higher than 37% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/lin-snow/Ech0/security/advisories/GHSA-pj6q-4vq4-r8cg referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 6.9 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
CNA 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L
CNA 4.0 6.9 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
GitHub 3.1 6.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L

Affected packages

ecosystem package affected fixed in
go github.com/lin-snow/Ech0
<1.4.8-0.20260503035905-cecc2c19b590
1.4.8-0.20260503035905-cecc2c19b590
go github.com/lin-snow/ech0
<1.4.8-0.20260503035905-cecc2c19b590
1.4.8-0.20260503035905-cecc2c19b590

Affected products

  • lin-snow Ech0

Classification

Weakness
  • CWE-770 Allocation of Resources Without Limits or Throttling
  • CWE-862 Missing Authorization

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.