Decompression bomb in ezstd:decompress_using_ddict/2 allows BEAM memory exhaustion via unbounded output buffer
Summary
| CVE | CVE-2026-119434 |
|---|---|
| State | PUBLISHED |
| Assigner | EEF |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-11-05 21:18:41 UTC |
| Updated | 2026-11-05 21:18:41 UTC |
| Description | Improper Handling of Highly Compressed Data (Data Amplification) vulnerability in silviucpp ezstd allows an attacker who supplies a zstd frame to ezstd:decompress_using_ddict/2 to exhaust memory and terminate the Erlang VM via a small frame that declares a very large content size. zstd_nif_decompress_using_ddict in c_src/ezstd_nif.cc reads the frame's declared content size with ZSTD_getFrameContentSize and passes it directly to enif_make_new_binary, without the 1 GiB MAX_BUFFER_SIZE check that ezstd:decompress/1 applies before allocating. A valid 65,550-byte frame of RLE blocks declaring 2 GiB is rejected by ezstd:decompress/1 but is fully allocated and decompressed by the dictionary path. The allocation happens inside a NIF, so when it exceeds the memory available to the VM the operating system kills the whole node rather than the calling process. This issue affects ezstd: from 1.0.5 before 1.2.5. |
Risk And Classification
Primary CVSS: v4.0 6.9 MEDIUM from 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
CVSS:4.0/AV:L/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
Problem Types: CWE-409 | CWE-409 CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 4.0 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | Secondary | 6.9 | MEDIUM | CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/C... |
| 4.0 | CNA | CVSS | 6.9 | MEDIUM | CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N |
| 3.1 | ADP | DECLARED | 6.2 | MEDIUM | CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
| 3.1 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | Secondary | 6.2 | MEDIUM | CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
CVSS v4.0 Breakdown
CVSS:4.0/AV:L/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
CVSS v3.1 Breakdown
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Vendor Declared Affected Products
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| github.com/silviucpp/ezstd/releases/tag/v1.2.5 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | |
| cna.erlef.org/cves/CVE-2026-119434.html | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | cna.erlef.org | |
| github.com/silviucpp/ezstd/commit/e34f4a4f6dc18d990d1cece2d5fceef8e934a195 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | |
| github.com/silviucpp/ezstd/commit/6730128b1d35eca02a2028671421471ff651f423 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | github.com | |
| osv.dev/vulnerability/EEF-CVE-2026-119434 | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | osv.dev | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Oz Kaiser (en)
CNA: Oz Kaiser (en)
CNA: Silviu Caragea (en)
CNA: Jonatan Männchen / EEF (en)
Additional Advisory Data
Workarounds
CNA: Replace calls to ezstd:decompress_using_ddict/2 with the streaming API: create a context with ezstd:create_decompression_context/1 using a small output buffer, attach the dictionary with ezstd:select_ddict/2, and decompress with ezstd:decompress_streaming/2. The streaming path decompresses into the caller-sized buffer and gives up with {error, decompressor_stuck} after 1000 chunks, so a 64 KiB buffer caps a single call at 64 MiB of output. Treat that error as a rejected input. Legitimate frames whose output exceeds 1000 times the buffer size fail the same way, so size the buffer for the largest expected payload.