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NVD / CVE Program· CNA Linux

CVE-2026-98079: btrfs: zstd: fix lost wakeup when waiting for a workspace

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.20% (FIRST EPSS).
  • Fixed version: Linux Linux 0de9f31d447ae71ab08c7850a321682f8d2907c3, 14d982762945d9945c60bbd48b77df194dd8e28d, 2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.159.1-1 on Azure Linux 3.0 Release Notes.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 0de9f31d447ae71ab08c7850a321682f8d2907c3, 14d982762945d9945c60bbd48b77df194dd8e28d, 2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 Release Notes; azl3 kernel 6.6.159.1-1 on Azure Linux 3.0 Release Notes or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

In the Linux kernel, the following vulnerability has been resolved: btrfs: zstd: fix lost wakeup when waiting for a workspace A writer can sleep forever in zstd_get_workspace() even though a workspace is free. When zstd_alloc_workspace() fails, the task is queued on zwsm->wait and schedules unconditionally, never re-testing the pool. zstd_put_workspace() publishes the workspace and then calls cond_wake_up(), which only wakes when a sleeper is already visible, so a workspace returned between the failed allocation and prepare_to_wait() wakes nobody. The window is wide: zstd_alloc_workspace() goes through kvmalloc() and may enter reclaim. Only a max level workspace triggers the wakeup and one is deliberately kept allocated as the fallback every waiter waits for, so once its wakeup is lost the writer stays in TASK_UNINTERRUPTIBLE until some other task happens to return one. Re-check the pool after prepare_to_wait() has published the waiter, and use the workspace if one turned up.

—No exploit Fix available
Published
Sep 25, 2026
Updated
Oct 21, 2026
EPSS
0.2% · 9th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.2%

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  • No public exploit code on record
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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

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

    • 5.1affected
    • 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 and later · before 14d982762945d9945c60bbd48b77df194dd8e28daffected · git
    • 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 and later · before 844603cf842ee67640d33f350e3fa60f3de7fad3affected · git
    • 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 and later · before d8f57049521948df5f50797141472fbbed3b0723affected · git
    • 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 and later · before 0de9f31d447ae71ab08c7850a321682f8d2907c3affected · git
    • 3f93aef535c8ea03e40cd8acf0753b3e6ed33e96 and later · before 2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7affected · git
    • before 5.1not affected · semver
    • 6.6.160 and later · up to and including 6.6.*not affected · semver
    • 6.12.114 and later · up to and including 6.12.*not affected · semver
    • 6.18.53 and later · up to and including 6.18.*not affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxfrom 0—
Debian:13linuxbefore 6.12.115-26.12.115-2
Debian:14linuxbefore 7.2.7-17.2.7-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-98076Sep 25, 2026 · tracing/probes: Fix use-after-free on field name/type of events with multiple probes
    0Monitor
  • ← EarlierCVE-2026-98077Sep 25, 2026 · netfilter: nf_conntrack_sip: fix OOB read in sip_skip_whitespace()
    0Monitor
  • Later →CVE-2026-98081Sep 25, 2026 · btrfs: zoned: finish active block group cleanup if call_zone_finish() fails
    0Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux0de9f31d447ae71ab08c7850a321682f8d2907c3Vendor (CNA)
Linux Linux14d982762945d9945c60bbd48b77df194dd8e28dVendor (CNA)
Linux Linux2acb9f3d1cc8f65dc81ed55e238cbf8e5b60bff7Vendor (CNA)
Linux Linux844603cf842ee67640d33f350e3fa60f3de7fad3Vendor (CNA)
Linux Linuxd8f57049521948df5f50797141472fbbed3b0723Vendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
azl3 kernel 6.6.159.1-1 on Azure Linux 3.0Release NotesMicrosoft (MSRC)
debian:linux6.12.115-2 · Debian:13Package registry (OSV)
debian:linux7.2.7-1 · Debian:14Package 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.

EPSS, last 120 days

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 researchers

Finders, 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.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

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.

Change log

  1. Fix✗ → ✓

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References

Show all references (4 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records