6.3

CVE-2026-64647: vercel next.js Improper Encoding or Escaping of Output

CVSS: 6.3v4.0MediumAnalyzed
AliasesCGA-2q38-fmpj-xj6hCGA-35h9-x4x8-49xrCGA-72mh-rggw-xm3v
Published 27-07-2026Last modified 27-07-2026
Open JSON

Vulnerability summary

CVE-2026-64647 is a medium (CVSS 6.3) Improper Encoding or Escaping of Output vulnerability in vercel next.js. EPSS estimates a 0.32% chance of exploitation in the next 30 days, higher than 23.3% of scored vulnerabilities.

Overall risk
25/100
0100
Medium · default modelHow is this calculated?
CVSS score
6.3/10
010
Medium · v4.0 (CVE.org)
EPSS score
0.32%
0%100%
Low · -0.03 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 0 · Related 1
CGA-HGC4-FH58-3WFW

Timeline

  1. 27-07-2026
    PublishedVulnerability first disclosed.
  2. 27-07-2026
    Last modifiedVulnerability information updated.

Description

Next.js is a React framework for building full-stack web applications. In versions 12.0.0 through 15.5.20 and 16.0.0 through 16.2.10, a server-side fetch with a request body may return a cached response body from a different request to the same URL but different body. Confidential data in the POST's response body would then leak to unauthorized requests. Though the request itself will not be deduped. This is only an issue when receiving request bodies with a content type charset other than UTF-8. For example, the UTF-16 byte sequences for 삃삃 and 섄섄 in the request body would share the same cache. This issue has been fixed in versions 15.5.21 and 16.2.11.

CVSS metrics

6 scores · 5 sources · 2 versions

EPSS trend

Probability

0.32%

Chance of exploitation in the next 30 days

Percentile

23%

Versus all other CVEs

30-day change

-0.03 pp

From 0.35% on 21-09-2026

21-09-202621-10-2026
EPSS score
0.32%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Chainguard14 products
  • cadence-webAll versions (No fix recorded)
  • commercial-chainloop-frontendAll versions (No fix recorded)
  • homepage< 1.13.2-r9 | < 1.13.2-r8
  • jitsucom-jitsu-console< 2.11.0-r30
  • keep-ui< 0.54.2-r1
Wolfi4 products
  • jitsucom-jitsu-console< 2.11.0-r30
  • langfuse-3< 3.224.1-r0
  • langfuse-3-compat< 3.225.7-r6
  • langfuse-3-worker< 3.224.1-r0
Npm1 product
  • next≥ 13.0.0, < 15.5.21 | ≥ 16.0.0, < 16.2.11
Vercel1 product
  • next.js≥ 13.0.0, < 15.5.21 | ≥ 16.0.0, < 16.2.11

4 vendors · 20 products

References

8 links