Vulnerability · RUSTSEC-2026-0348
Brotli certificate decompression can allocate up to 1 GiB before authentication
Published Oct 14, 2026 · catalog updated Oct 14, 2026 · RustSec Rust
Open the advisory
Exploitation likelihood is not on this record for RUSTSEC-2026-0348. A missing EPSS score is not a low risk. Compare RustSec Rust with the linked advisory before you change production.
Gaps on this record
- No vendor fix or required action is stored. Compare the linked advisory before you change production.
- EPSS is missing. A missing score is not a low risk.
- Severity
- Low3.7
- Known exploitation
- Not in CISA/VulnCheck KEV
- EPSS
- Awaiting synchronization with FIRST
- Remediation
- Advisory link
- Affected products
- crates.io rustls
The built-in Brotli certificate decompressor (enabled by the non-default crate feature) bounded the size of the decompressed output, but accepted a peer-selected history window. Brotli's large-window extension was enabled, so a five-byte header could cause an allocation of 1 GiB. A peer can abort a process whose allocator cannot satisfy that request. No trusted certificate is required by the attacker. Affected configurations are: - clients that enable the feature and connect to a malicious server, and - servers that enable the feature and request client certificates. Applications that do not enable the feature are not affected.
Are you affected?
Enter the version you run. The result uses only the ranges stored on this record.
The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.
- crates.io rustls0.23.9 → 0.23.46
How to fix RUSTSEC-2026-0348
Recommended remediation
A patch or advisory reference is linked. Open the original publisher for availability by product version.
Official advisories
What to do
Three questions, each answered from this record only. Confirm the vendor advisory before you patch.
Should you patch?
Exploitation likelihood is not on this record for RUSTSEC-2026-0348. A missing EPSS score is not a low risk. Compare RustSec Rust with the linked advisory before you change production.
Which versions are affected?
Compare what you have installed with 0.23.9 → 0.23.46. Compare the installed version with the linked vendor advisory before you change production.
What should an analyst verify?
No weakness class is stored. EPSS is not on this record yet. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.
Code
The project this record applies to. Exploit listings stay in References.
Timeline
Detection, updates, and resolution for this record.
Oct 14, 2026 · GitHub Advisory Database
Detected
The built-in Brotli certificate decompressor (enabled by the non-default crate feature) bounded the size of the decompressed output, but accepted a peer-selected history window. Brotli's large-window extension was enabled, so a five-byte header could cause an allocation of 1 GiB. A peer can abort a process whose allocator cannot satisfy that request. No trusted certificate is required by the attac
Oct 14, 2026 · GitHub Advisory Database
Fix available
rustls fixed in 0.23.46
Oct 14, 2026 · GitHub Advisory Database
Fix available
rustls fixed in 0.23.46
Oct 14, 2026 · GitHub Advisory Database
Updated
The built-in Brotli certificate decompressor (enabled by the non-default crate feature) bounded the size of the decompressed output, but accepted a peer-selected history window. Brotli's large-window extension was enabled, so a five-byte header could cause an allocation of 1 GiB. A peer can abort a process whose allocator cannot satisfy that request. No trusted certificate is required by the attac
Sources
- GitHub Advisory DatabasePackage advisoryGHSA-h2v8-394m-p7vv
GitHub Advisory Database record mirrored by OSV.
github.com - OpenSSF OSV / OSV ScannerPackage advisoryRUSTSEC-2026-0348
Brotli certificate decompression can allocate up to 1 GiB before authentication
osv.dev - RustSec Advisory DBVendor advisoryRUSTSEC-2026-0348
The built-in Brotli certificate decompressor (enabled by the non-default crate feature) bounded the size of the decompressed output, but accepted a peer-selected history window. Brotli's large-window extension was enabled, so a five-byte header could cause an allocation of 1 GiB.
crates.io
References
Freshness
Last verified in this catalog Oct 14, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.