crypto: zstd - fix double-free in per-CPU stream cleanup
In the Linux kernel, the following vulnerability has been resolved: crypto: zstd - fix double-free in per-CPU stream cleanup The crypto/zstd module has a double-free bug that occurs when multiple tfms are allocated and freed. The issue happens because zstd_streams (per-CPU contexts) are freed in zstd_exit() during every tfm destruction, rather than being managed at the module level. When multiple tfms exist, each tfm exit attempts to free the same shared per-CPU streams, resulting in a double-free. This leads to a stack trace similar to: BUG: Bad page state in process kworker/u16:1 pfn:106fd93 page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x106fd93 flags: 0x17ffffc0000000(node=0|zone=2|lastcpupid=0x1fffff) page_type: 0xffffffff() raw: 0017ffffc0000000 dead000000000100 dead000000000122 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: nonzero entire_mapcount Modules linked in: ... CPU: 3 UID: 0 PID: 2506 Comm: kworker/u16:1 Kdump: loaded Tainted: G B Hardware name: ... Workqueue: btrfs-delalloc btrfs_work_helper Call Trace: <TASK> dump_stack_lvl+0x5d/0x80 bad_page+0x71/0xd0 free_unref_page_prepare+0x24e/0x490 free_unref_page+0x60/0x170 crypto_acomp_free_streams+0x5d/0xc0 crypto_acomp_exit_tfm+0x23/0x50 crypto_destroy_tfm+0x60/0xc0 ... Change the lifecycle management of zstd_streams to free the streams only once during module cleanup.
- Published
- Dec 16, 2025
- Updated
- Jun 17, 2026
- EPSS
- 0.2% · 7th percentile
- CWE
- —
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Report tools
Action score
0
Monitor
Low priority for now.
- CVSS
- 0 / 40 · —
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.2%
Affected systems
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Versions reported by the vendor
Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.
Linux Linux
- 6.17affected
- f5ad93ffb54119a8dc5e18f070624d4ead586969 and later · before dc0f4509b0ed5d82bef78e058db0ac4df04d0695affected · git
- f5ad93ffb54119a8dc5e18f070624d4ead586969 and later · before e983feaa79de1e46c9087fb9f02fedb0e5397ce6affected · git
- f5ad93ffb54119a8dc5e18f070624d4ead586969 and later · before 48bc9da3c97c15f1ea24934bcb3b736acd30163daffected · git
- before 6.17not affected · semver
- 6.17.12 and later · up to and including 6.17.*not affected · semver
- 6.18.1 and later · up to and including 6.18.*not affected · semver
- 6.19 and laternot affected · original_commit_for_fix
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:14 | linux | before 6.17.12-1 | 6.17.12-1 |
| openSUSE:Tumbleweed | kernel-source | before 6.18.2-1.1 | 6.18.2-1.1 |
Same product
linux: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation40Plan
- CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment40Plan
- CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()40Plan
- CVE-2026-74309vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler40Plan
- CVE-2026-74280crypto: marvell/octeontx - fix DMA cleanup using wrong loop index40Plan
- CVE-2026-74279crypto: cavium/cpt - fix DMA cleanup using wrong loop index40Plan
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| Linux Linux | 48bc9da3c97c15f1ea24934bcb3b736acd30163d | Vendor (CNA) |
| Linux Linux | dc0f4509b0ed5d82bef78e058db0ac4df04d0695 | Vendor (CNA) |
| Linux Linux | e983feaa79de1e46c9087fb9f02fedb0e5397ce6 | Vendor (CNA) |
| debian:linux | 6.17.12-1 · Debian:14 | Package registry (OSV) |
| opensuse:kernel-source | 6.18.2-1.1 · openSUSE:Tumbleweed | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
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Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
No CVSS vector for this record, so attack conditions can't be derived.
Weakness class (CWE)
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Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
MITRE has no CAPEC/ATT&CK mapping for this CWE.
Noroxi analysis
No Noroxi analysis for this record yet
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We use this product, ask for helpChange log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
- git.kernel.org/stable/c/48bc9da3c97c15f1ea24934bcb3b736acd30163d
- git.kernel.org/stable/c/dc0f4509b0ed5d82bef78e058db0ac4df04d0695
- git.kernel.org/stable/c/e983feaa79de1e46c9087fb9f02fedb0e5397ce6
Vendor advisories and official records. Exploit/PoC links are deliberately left out.