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HIGH severity

GHSA-5vjc-7cxw-4w6j — thumbor

HIGHFix: thumbor/thumbor@3f38fe1

GHSA-5vjc-7cxw-4w6j is a high-severity (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in thumbor. A fix is available for thumbor — see the affected versions and patch details below.

Thumbor has Regex Denial of Service (ReDoS) in `convolution` filter

Also known asCVE-2026-53504PYSEC-2026-3616
Published
Jul 31, 2026
Updated
Aug 4, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Sep 17, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.

Exploitation and automatability from CISA’s SSVC triage for GHSA-5vjc-7cxw-4w6j.

EPSS Exploitation Probability

via FIRST.org ↗
0.4%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs35th percentile — riskier than 35% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

How urgent is this, really

GHSA-5vjc-7cxw-4w6j plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.

Where this sits among everything scored

Of 374,847 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.

Real-World Exposure

1 pkg affected
🐍thumbor

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Summary

The regular expression used to parse the convolution filter exhibits exponential-time backtracking for certain inputs, enabling a Regular Expression Denial of Service (ReDoS).

Details

The RegExp for convolution is defined as convolution\((?:\s*((?:[-]?[\d]+\.?[\d]*[;])*(?:[-]?[\d]+\.?[\d]*))\s*)(?:,\s*([\d]+)\s*)(?:,\s*([Tt]rue|[Ff]alse|1|0)\s*)?\). Within this expression a dangerous subpattern effectively behaves like (\d+)*,\d+.

PoC

A filter string containing many repeated values will exhaust re.match:

The evaluation occurs on https://github.com/thumbor/thumbor/blob/master/thumbor/filters/__init__.py#L189.

Impact

A specially crafted URL will lead to denial of service, as new images won't be processed until re.match returns.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIthumborall versions7.8.0pip install --upgrade 'thumbor==7.8.0'

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for thumbor, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update thumbor to 7.8.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-5vjc-7cxw-4w6j is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-5vjc-7cxw-4w6j can be triaged on real exposure rather than presence alone.

Tailored to GHSA-5vjc-7cxw-4w6j. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Summary The regular expression used to parse the `convolution` filter exhibits exponential-time backtracking for certain inputs, enabling a Regular Expression Denial of Service (ReDoS). ### Details The RegExp for `convolution` is defined as `convolution\((?:\s*((?:[-]?[\d]+\.?[\d]*[;])*(?:[-]?[\d]+\.?[\d]*))\s*)(?:,\s*([\d]+)\s*)(?:,\s*([Tt]rue|[Ff]alse|1|0)\s*)?\)`. Within this expression a dangerous subpattern effectively behaves like `(\d+)*,\d+`. ### PoC A filter string containing many repeated values will exhaust `re.match`: - `convolution(-11;-11;-11;-11;-11;-11;-11;-11;-11;-11;-11
O3 Security · Impact-Aware SCA

Is GHSA-5vjc-7cxw-4w6j in your dependencies?

O3 Security finds GHSA-5vjc-7cxw-4w6j across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

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GHSA-5vjc-7cxw-4w6j: thumbor (High 7.5) | O3 Security