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Fencer Vulns
high 8.2

CVE-2026-53500 json

Thumbor treats ALLOWED_SOURCES string patterns as unescaped regex, allowing hostname bypass via wildcard dot

published 2026-07-31 3 mo ago modified 2026-09-08 2 mo ago also GHSA-6x26-6r6f-m537 , PYSEC-2026-3617 , EUVD-2026-51597

cvss
8.2
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.5%
EPSS 0.5% chance of exploitation in 30 days, percentile 42%
public exploits
0
none known

Summary

Thumbor is an open-source photo thumbnail service by globo.com. Prior to 7.8.0, the ALLOWED_SOURCES configuration passes plain strings to re.match() without escaping dots, so a hostname differing at dot positions can match the allowlist. 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-2026-53500

CISA SSVC

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

Exploit prediction

0.50% chance of exploitation in the next 30 days, higher than 42% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/thumbor/thumbor/security/advisories/GHSA-6x26-6r6f-m537 referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L
OSV 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L
GitHub 3.1 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:L

Affected packages

ecosystem package affected fixed in
pypi thumbor
<7.8.0
7.8.0

Affected products

  • thumbor thumbor

Classification

Weakness
  • CWE-918 Server-Side Request Forgery
  • CWE-1333 Inefficient Regular Expression Complexity

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.