CVE-2025-25193

Summary

An unsafe reading of environment file could potentially cause a denial of service in Netty. When loaded on an Windows application, Netty attemps to load a file that does not exist. If an attacker creates such a large file, the Netty application crash.

Details

A similar issue was previously reported in https://github.com/netty/netty/security/advisories/GHSA-xq3w-v528-46rv This issue was fixed, but the fix was incomplete in that null-bytes were not counted against the input limit.

PoC

The PoC is the same as for https://github.com/netty/netty/security/advisories/GHSA-xq3w-v528-46rv with the detail that the file should only contain null-bytes; 0x00. When the null-bytes are encountered by the InputStreamReader, it will issue replacement characters in its charset decoding, which will fill up the line-buffer in the BufferedReader.readLine(), because the replacement character is not a line-break character.

Impact

Impact is the same as https://github.com/netty/netty/security/advisories/GHSA-xq3w-v528-46rv

A client might overload the server by issue frequent RST frames. This can cause a massive amount of load on the remote system and so cause a DDOS attack.

Impact

This is a DDOS attack, any http2 server is affected and so you should update as soon as possible.

Patches

This is patched in version 4.1.100.Final.

Workarounds

A user can limit the amount of RST frames that are accepted per connection over a timeframe manually using either an own Http2FrameListener implementation or an ChannelInboundHandler implementation (depending which http2 API is used).

References

• https://www.cve.org/CVERecord?id=CVE-2023-44487
• https://blog.cloudflare.com/technical-breakdown-http2-rapid-reset-ddos-attack/
• https://cloud.google.com/blog/products/identity-security/google-cloud-mitigated-largest-ddos-attack-peaking-above-398-million-rps/

Red Hat Lightwell has released io.netty:netty-common 4.1.100.Final-rhlw-00001 with backported fixes for CVE-2024-47535 and CVE-2025-25193.

CVE-2024-47535: Denial of Service attack on windows app using Netty

CVE-2025-25193: Denial of Service attack on windows app using Netty

This patched artifact is a drop-in replacement for io.netty:netty-common 4.1.100.Final from Maven Central.

Root has patched GHSA-xpw8-rcwv-8f8p in the io.root.io.netty:netty-codec-http2 package for Root:Maven. Multiple fixed versions available.

Netty, an asynchronous, event-driven network application framework, has a vulnerability in versions up to and including 4.1.118.Final. An unsafe reading of environment file could potentially cause a denial of service in Netty. When loaded on an Windows application, Netty attempts to load a file that does not exist. If an attacker creates such a large file, the Netty application crash. A similar issue was previously reported as CVE-2024-47535. This issue was fixed, but the fix was incomplete in that null-bytes were not counted against the input limit. Commit d1fbda62d3a47835d3fb35db8bd42ecc205a5386 contains an updated fix.

TuxCare rebuilt io.netty:netty-common to address 1 CVE. Fixed in 4.1.115.Final-tuxcare.3.

TuxCare rebuilt 43 io.netty packages to address 12 CVEs. Fixed in 4.1.63.Final-tuxcare.2.

TuxCare rebuilt 47 io.netty packages to address 12 CVEs. Fixed in 4.1.93.Final-tuxcare.1.

TuxCare rebuilt 4 io.netty packages to address 5 CVEs. Fixed in 4.1.117.Final-tuxcare.1.

TuxCare rebuilt 47 io.netty packages to address 41 CVEs. Fixed in 4.1.112.Final-tuxcare.6.

TuxCare rebuilt 47 io.netty packages to address 62 CVEs. Fixed in 4.1.111.Final-tuxcare.1.

TuxCare rebuilt 47 io.netty packages to address 61 CVEs. Fixed in 4.1.108.Final-tuxcare.1.

TuxCare rebuilt 47 io.netty packages to address 61 CVEs. Fixed in 4.1.107.Final-tuxcare.1.

TuxCare rebuilt 47 io.netty packages to address 62 CVEs. Fixed in 4.1.94.Final-tuxcare.1.

TuxCare rebuilt 7 io.netty packages to address 15 CVEs. Fixed in 4.1.101.Final-tuxcare.1.

TuxCare rebuilt 7 io.netty packages to address 13 CVEs. Fixed in 4.1.100.Final-tuxcare.1.

TuxCare rebuilt 13 io.netty packages to address 24 CVEs. Fixed in 4.1.114.Final-tuxcare.1.

TuxCare rebuilt 10 io.netty packages to address 15 CVEs. Fixed in 4.1.113.Final-tuxcare.1.

These are all security issues fixed in the netty-4.1.118-1.1 package on the GA media of openSUSE Tumbleweed.

This update for netty, netty-tcnative fixes the following issues:

• CVE-2025-24970: incorrect validation of packets by SslHandler can lead to a native crash. (bsc#1237037)
• CVE-2025-25193: unsafe reading of environment files can lead to an application crash. (bsc#1237038)

Update to netty version 4.1.118 and netty-tcnative version 2.0.70 Final.

Other fixes:

• Fix recycling in CodecOutputList.
• StreamBufferingEncoder: do not send header frame with priority by default.
• Notify event loop termination future of unexpected exceptions.
• Fix AccessControlException in GlobalEventExecutor.
• AdaptivePoolingAllocator: round chunk sizes up and reduce chunk release frequency.
• Support BouncyCastle FIPS for reading PEM files.
• Dns: correctly encode DnsPtrRecord.
• Provide Brotli settings without com.aayushatharva.brotli4j dependency.
• Make DefaultResourceLeak more resilient against OOM.
• OpenSslSession: add support to defensively check for peer certs.
• SslHandler: ensure buffers are never leaked when wrap(...) produces SSLException.
• Correcly handle comments appended to nameserver declarations.
• PcapWriteHandler: apply fixes so that the handler can append to an existing PCAP file when writing the global header.
• PcapWriteHandler: allow output of PCAP files larger than 2GB.
• Fix bugs in BoundedInputStream.
• Fix HTTP header validation bug.
• AdaptivePoolingAllocator: fix possible race condition in method offerToQueue(...).
• AdaptivePoolingAllocator: make sure the sentinel object Magazine.MAGAZINE_FREED not be replaced.
• Only try to use Zstd and Brotli if the native libs can be loaded.
• Bump BlockHound version to 1.0.10.RELEASE.
• Add details to TooLongFrameException message.
• AdaptivePoolingAllocator: correctly reuse chunks.
• AdaptivePoolingAllocator: don't fail when we run on a host with 1 core.
• AdaptivePoolingAllocator: correctly re-use central queue chunks and avoid OOM issue.
• Fix several memory management (leaks and missing checks) issues.