Open-Source Security Intelligence

Know every vulnerability
before it knows you.

DevGuard continuously monitors your dependencies and alerts you when CVEs like this one affect your stack — with real-time threat intelligence built for developers.

Search

GHSA-8xx6-hgc6-gc2m

HighCVSS 7.5 / 10
Published Sep 8, 2026·Last modified Sep 8, 2026
Affected Components(1)
PyPI logohttpx2
< 2.12.0
Description

Summary

When decoding a compressed response body (gzip, deflate, br, or zstd), HTTPX2 fully decompressed each network read before yielding content to the application. A small compressed input could therefore cause a large intermediate memory allocation, even when the application streamed the response to keep memory usage bounded.

Details

HTTPX2's default transport reads the socket in pieces of up to 64 KiB. Before 2.12.0, each piece was inflated completely into one intermediate allocation before any decompressed bytes were yielded.

At DEFLATE's maximum compression ratio of roughly 1032:1, a 64 KiB compressed chunk can expand to about 64 MiB in one allocation. Brotli and Zstandard responses can cause similarly large amplification. Streaming the response did not prevent these transient allocations.

Impact

Applications that fetch resources from untrusted or attacker-influenced servers - such as webhook receivers, link unfurlers, crawlers, SSRF-reachable fetchers, and redirect followers - can experience memory pressure or out-of-memory termination when processing a malicious compressed response. No authentication or user interaction is required beyond issuing a request to the server.

Mitigation

Upgrade to HTTPX2 2.12.0 or later. Patched versions decompress responses incrementally with bounded intermediate buffers, including responses with multiple content encodings.

Upload your SBOM

Upload your own SBOM in CycloneDX 1.6 or higher (JSON) directly here to check your vulnerabilities.

Risk Scores
Base Score
7.5

The vulnerability can be exploited over the network without needing physical access. It is easy for an attacker to exploit this vulnerability. An attacker does not need any special privileges or access rights. No user interaction is needed for the attacker to exploit this vulnerability. The impact is confined to the system where the vulnerability exists. There is a high impact on the availability of the system.

Threat Intelligence
6.9

Exploitation attempts have been detected. Elevated vigilance and prompt remediation are advised.

EPSS
0.63%

The exploit probability is very low. The vulnerability is unlikely to be exploited in the next 30 days.

Exploit
Not available

We did not find any exploit available. Neither in GitHub repositories nor in the Exploit-Database.

Browse More

Scan your project

Continuously monitor your dependencies and get alerted when vulnerabilities like this one affect your stack.

Checkout DevGuard