Vulnerability in thumbor (UBUNTU-CVE-2026-53501)

Summary

Vulnerability in thumbor (UBUNTU-CVE-2026-53501). Data can be tampered with by attackers. Mitigation: upgrade to 7.8.0 or later.

Original description

The description as published by the source.

Thumbor is an open-source photo thumbnail service by globo.com. Prior to 7.8.0, Thumbor’s HMAC validation can be bypassed due to the use of Python’s .replace() when removing the signature from the URL before validation. Since .replace() removes all occurrences of the substring, an attacker can insert the same signature multiple times in the URL and manipulate the final URL used for validation. This allows crafting URLs where the validated string differs from the actual requested resource, enabling loading images from unintended domains or paths. This issue is fixed in 7.8.0.

Source: OSV.dev (Open Source Vulnerabilities) OSV

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as UBUNTU-CVE-2026-53501 has been found in thumbor.
Data can be tampered with by attackers.
What to do: upgrade thumbor to 7.8.0 or later.
If unsure, ask your IT team or search "thumbor UBUNTU-CVE-2026-53501" on the vendor's site.

UBUNTU-CVE-2026-53501 (thumbor)
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: 7.8.0 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

A vulnerability (unclassified) exists in thumbor.

📍 Affected scope

Check the vendor advisory for the affected versions of thumbor.

🔥 Severity

Severity: ?. Data can be tampered with by attackers.

🔧 How to fix

Update to 7.8.0.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'thumbor' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

Concrete steps and command examples for SOC/SRE teams to execute in order

1
Identify exposure identify
```
grep -r 'thumbor' . | grep -v node_modules
```
リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で thumbor を grep し、稼働しているサービス・バージョンを把握する。
2
Apply patch patch
```
Upgrade thumbor to 7.8.0
```
ステージング環境で 7.8.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
3
Post-deployment verification verify
```
Confirm patched version is live in production
```
パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

Ubuntu:26.04:LTS thumbor

[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]

References

report ubuntu.com
report cve.org
report github.com
report github.com
report github.com