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CVE-2026-89778· NVD / CVE Program· CNA Linux

isofs: fix out-of-bounds page array access on empty zisofs block

In the Linux kernel, the following vulnerability has been resolved: isofs: fix out-of-bounds page array access on empty zisofs block zisofs_uncompress_block()'s empty-block fast path returns pcount << PAGE_SHIFT, ignoring the incoming poffset, unlike the decompression path which returns bytes produced relative to poffset. zisofs_fill_pages() uses that return to advance its page cursor, so when the zisofs block size is below PAGE_SIZE and a sub-page block leaves poffset partway into a page, a following empty block over-counts and advances pages[] one element past its end, after which "if (poffset && *pages)" reads pages[1] out of bounds. rock.c only rejects a block-size shift > 17, so a crafted "ZF" Rock Ridge record can set it below PAGE_SHIFT; the bug is reached by an ordinary read() of a compressed file on such a mounted ISO9660 image. Return the byte count relative to poffset and zero only [poffset, PAGE_SIZE) of the first page, matching the decompression path. The page-aligned case (poffset == 0) is unaffected. BUG: KASAN: slab-out-of-bounds in zisofs_read_folio (fs/isofs/compress.c:290) Read of size 8 at addr ffff88800f5eac48 by task exploit/142 zisofs_read_folio (fs/isofs/compress.c:290) read_pages (mm/readahead.c:184) ... filemap_read (mm/filemap.c:2814) vfs_read (fs/read_write.c:574) __x64_sys_pread64 (fs/read_write.c:769) do_syscall_64 (arch/x86/entry/syscall_64.c:94) entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) The buggy address is located 0 bytes to the right of the allocated 8-byte region in the kmalloc-8 cache

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Sep 16, 2026
Updated
Sep 16, 2026
EPSS
0.7% · 53th percentile
CWE
—
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Report tools

JSON

Action score

39

Monitor

Low priority for now.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.7%

CNA vs NVD score

NVD
—
CNA · Linux
9.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

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

    • 2.6.33affected
    • 59bc055211b8d266ab6089158058bf8268e02006 and later · before 8b994ac5778a725982fd6a8a3afcaa068d4a93e3affected · git
    • 59bc055211b8d266ab6089158058bf8268e02006 and later · before ad3249cdf9d4ba34bb8b1ff3956a4020fdfb5b0aaffected · git
    • 59bc055211b8d266ab6089158058bf8268e02006 and later · before 85904076cece72ee3194646ad7ac8e6659d999aaaffected · git
    • 59bc055211b8d266ab6089158058bf8268e02006 and later · before f03425dcbe04aec3c27b9917e97d7d23a2908ddaaffected · git
    • 59bc055211b8d266ab6089158058bf8268e02006 and later · before cd616aa0449a772a6956abf03358f0ff31720580affected · git
    • 59bc055211b8d266ab6089158058bf8268e02006 and later · before 9c6eace8d07e90f038c89eb3b756d65a7e259d48affected · git
    • 59bc055211b8d266ab6089158058bf8268e02006 and later · before 68d4d3e78150c7ed7d1195af63ad1e6ace30c661affected · git
    • before 2.6.33not affected · semver
    • 5.15.221 and later · up to and including 5.15.*not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxall versions—
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.6-17.2.6-1

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
  • CVE-2026-74309vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
    40Plan
  • CVE-2026-74280crypto: marvell/octeontx - fix DMA cleanup using wrong loop index
    40Plan
  • CVE-2026-74279crypto: cavium/cpt - fix DMA cleanup using wrong loop index
    40Plan

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 Linux68d4d3e78150c7ed7d1195af63ad1e6ace30c661Vendor (CNA)
Linux Linux85904076cece72ee3194646ad7ac8e6659d999aaVendor (CNA)
Linux Linux8b994ac5778a725982fd6a8a3afcaa068d4a93e3Vendor (CNA)
Linux Linux9c6eace8d07e90f038c89eb3b756d65a7e259d48Vendor (CNA)
Linux Linuxad3249cdf9d4ba34bb8b1ff3956a4020fdfb5b0aVendor (CNA)
Linux Linuxcd616aa0449a772a6956abf03358f0ff31720580Vendor (CNA)
Linux Linuxf03425dcbe04aec3c27b9917e97d7d23a2908ddaVendor (CNA)
azl3 kernel 6.6.150.1-1 on Azure Linux 3.0—Microsoft (MSRC)
azl3 kernel 6.6.152.1-1 on Azure Linux 3.06.6.157.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.12.111-1 · Debian:13Package 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+1% in 7 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.

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Bug bounty scope

No known public program.

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

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

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CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

nvd-secondary

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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Change log

  1. Fix✗ → ✓

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References

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

All records