CVE-2026-128242 json
actix-http before 3.20.1 and actix-web before 4.18.2 Decompression Bomb DoS via encoding::Decoder
published 8d ago modified 1h ago also EUVD-2026-125050 , GHSA-qph8-7859-gq2f , RUSTSEC-2026-0447 , RUSTSEC-2026-0448
- cvss
- 7.5
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.9%
- EPSS 0.9% chance of exploitation in 30 days, percentile 61%
- public exploits
- 0
- none known
Summary
actix-http before 3.20.1 and actix-web before 4.18.2 contain an unbounded decompression vulnerability in encoding::Decoder that lets remote attackers exhaust memory and CPU via compressed bodies. Attackers can send small highly compressed gzip, deflate, Brotli or zstd request bodies to Json, Form, Bytes or String extractors, or serve them to awc clients, causing denial of service.
Patch / fix
- crates.io actix-web 4.18.2
- crates.io actix-http 3.20.1
- actix actix-http 3.20.1
- actix actix-web 4.18.2
Is CVE-2026-128242 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- none
- Automatable
- yes
- Technical impact
- partial
- Assessed
- yesterday
Exploit prediction
0.93% chance of exploitation in the next 30 days, higher than 61% of all scored CVEs (FIRST EPSS, 2026-11-14).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 4.0 | 8.7 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N |
| CNA | 3.1 | 7.5 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| CNA | 4.0 | 8.7 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| crates.io | actix-web | >=0.0.0-0, <4.18.2 |
4.18.2 |
| crates.io | actix-http | >=0.0.0-0, <3.20.1 |
3.20.1 |
Affected products
- actix actix-http
- actix actix-web
Classification
- Weakness
-
- CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)
References
-
github.com
/actix/actix-web/commit/41b54d23ea04f66758c15de7e4ab18325cd25280
patch, web
-
github.com
/actix/actix-web/commit/0d0be61bd757027bfcecbc53df1b7a600f21ecd0
patch, web
-
github.com
/actix/actix-web/security/advisories/GHSA-qph8-7859-gq2f
vendor-advisory, advisory
-
rustsec.org
/advisories/RUSTSEC-2026-0448.html
third-party-advisory, advisory
-
github.com
/actix/actix-web/blob/actix-http-v3.20.0/actix-http/src/encoding/decoder.rs#L239-L301
technical-description
-
github.com
/actix/actix-web/releases/tag/actix-http-v3.20.1
release-notes
-
github.com
/actix/actix-web/releases/tag/actix-web-v4.18.2
release-notes
-
github.com
/actix/actix-web
product
-
vulncheck.com
/advisories/actix-http-before-3.20.1-and-actix-web-before-4.18.2-decompression-bomb-dos-via-encoding-decoder
third-party-advisory
-
crates.io
/crates/actix-web
package
-
rustsec.org
/advisories/RUSTSEC-2026-0447.html
advisory
-
crates.io
/crates/actix-http
package
Sources
- CVE List CVE-2026-128242
- NVD CVE-2026-128242
- OSV RUSTSEC-2026-0447
- OSV RUSTSEC-2026-0448
- Maintainer advisory GHSA-qph8-7859-gq2f
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
The maintainers of actix/actix-web published their own advisory on GitHub. Reviewed sources take precedence over it.