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Fencer Vulns
high 8.7

CVE-2026-53502 json

Thumbor has path traversal via post-validation URL decoding bypass in file_loader

published 2026-07-31 3 mo ago modified 2026-09-08 2 mo ago also GHSA-cj54-hpcc-gj6h , PYSEC-2026-3618 , EUVD-2026-51612

cvss
8.7
version 4.0, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 44%
public exploits
0
none known

Summary

Thumbor is an open-source photo thumbnail service by globo.com. Prior to 7.8.0, file_loader decodes percent-encoded path segments after its root-boundary validation, allowing traversal outside FILE_LOADER_ROOT_PATH through watermark or frame filter input. This issue is fixed in 7.8.0.

Patch / fix

  • pypi thumbor 7.8.0
  • thumbor Debian 14 7.8.0-1

debian advisories DEBIAN-CVE-2026-53502

CISA SSVC

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

Exploit prediction

0.52% chance of exploitation in the next 30 days, higher than 44% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/thumbor/thumbor/security/advisories/GHSA-cj54-hpcc-gj6h referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
CNA 4.0 8.7 CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/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

Affected packages

ecosystem package affected fixed in
pypi thumbor
<7.8.0
7.8.0

Affected products

  • thumbor thumbor

Classification

Weakness
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory

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.