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NVD / CVE Program· CNA Linux

CVE-2023-53642: x86: fix clear_user_rep_good() exception handling annotation

Noroxi assessment

Priority: Monitor (action score 22/100)

  • 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: 0.16% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 76ce32682635fe907e0f8e64e039e773e5c7508f, 90510aed20a26e1a4dede4ef6b640e6a4122f38f, b805d212c394f291f116b12c53401e7ba0c4d408.

Low priority for now. Upgrade to Linux Linux 76ce32682635fe907e0f8e64e039e773e5c7508f, 90510aed20a26e1a4dede4ef6b640e6a4122f38f, b805d212c394f291f116b12c53401e7ba0c4d408 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: x86: fix clear_user_rep_good() exception handling annotation This code no longer exists in mainline, because it was removed in commit d2c95f9d6802 ("x86: don't use REP_GOOD or ERMS for user memory clearing") upstream. However, rather than backport the full range of x86 memory clearing and copying cleanups, fix the exception table annotation placement for the final 'rep movsb' in clear_user_rep_good(): rather than pointing at the actual instruction that did the user space access, it pointed to the register move just before it. That made sense from a code flow standpoint, but not from an actual usage standpoint: it means that if user access takes an exception, the exception handler won't actually find the instruction in the exception tables. As a result, rather than fixing it up and returning -EFAULT, it would then turn it into a kernel oops report instead, something like: BUG: unable to handle page fault for address: 0000000020081000 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page ... RIP: 0010:clear_user_rep_good+0x1c/0x30 arch/x86/lib/clear_page_64.S:147 ... Call Trace: __clear_user arch/x86/include/asm/uaccess_64.h:103 [inline] clear_user arch/x86/include/asm/uaccess_64.h:124 [inline] iov_iter_zero+0x709/0x1290 lib/iov_iter.c:800 iomap_dio_hole_iter fs/iomap/direct-io.c:389 [inline] iomap_dio_iter fs/iomap/direct-io.c:440 [inline] __iomap_dio_rw+0xe3d/0x1cd0 fs/iomap/direct-io.c:601 iomap_dio_rw+0x40/0xa0 fs/iomap/direct-io.c:689 ext4_dio_read_iter fs/ext4/file.c:94 [inline] ext4_file_read_iter+0x4be/0x690 fs/ext4/file.c:145 call_read_iter include/linux/fs.h:2183 [inline] do_iter_readv_writev+0x2e0/0x3b0 fs/read_write.c:733 do_iter_read+0x2f2/0x750 fs/read_write.c:796 vfs_readv+0xe5/0x150 fs/read_write.c:916 do_preadv+0x1b6/0x270 fs/read_write.c:1008 __do_sys_preadv2 fs/read_write.c:1070 [inline] __se_sys_preadv2 fs/read_write.c:1061 [inline] __x64_sys_preadv2+0xef/0x150 fs/read_write.c:1061 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd which then looks like a filesystem bug rather than the incorrect exception annotation that it is. [ The alternative to this one-liner fix is to take the upstream series that cleans this all up: 68674f94ffc9 ("x86: don't use REP_GOOD or ERMS for small memory copies") 20f3337d350c ("x86: don't use REP_GOOD or ERMS for small memory clearing") adfcf4231b8c ("x86: don't use REP_GOOD or ERMS for user memory copies") * d2c95f9d6802 ("x86: don't use REP_GOOD or ERMS for user memory clearing") 3639a535587d ("x86: move stac/clac from user copy routines into callers") 577e6a7fd50d ("x86: inline the 'rep movs' in user copies for the FSRM case") 8c9b6a88b7e2 ("x86: improve on the non-rep 'clear_user' function") 427fda2c8a49 ("x86: improve on the non-rep 'copy_user' function") * e046fe5a36a9 ("x86: set FSRS automatically on AMD CPUs that have FSRM") e1f2750edc4a ("x86: remove 'zerorest' argument from __copy_user_nocache()") 034ff37d3407 ("x86: rewrite '__copy_user_nocache' function") with either the whole series or at a minimum the two marked commits being needed to fix this issue ]

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Oct 7, 2025
Updated
Jun 17, 2026
EPSS
0.1% · 5th percentile
CWE
—

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

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  • A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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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.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel6.1 and later · before 6.1.29
  • linux linux kernel6.2 and later · before 6.2.16
  • linux linux kernel6.3 and later · before 6.3.3

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

    • 6.1affected
    • 0db7058e8e23e6bbab1b4747ecabd1784c34f50b and later · before 76ce32682635fe907e0f8e64e039e773e5c7508faffected · git
    • 0db7058e8e23e6bbab1b4747ecabd1784c34f50b and later · before 90510aed20a26e1a4dede4ef6b640e6a4122f38faffected · git
    • 0db7058e8e23e6bbab1b4747ecabd1784c34f50b and later · before b805d212c394f291f116b12c53401e7ba0c4d408affected · git
    • 0db7058e8e23e6bbab1b4747ecabd1784c34f50b and later · before e046fe5a36a970bc14fbfbcb2074a48776f6b671affected · git
    • before 6.1not affected · semver
    • 6.1.29 and later · up to and including 6.1.*not affected · semver
    • 6.2.16 and later · up to and including 6.2.*not affected · semver
    • 6.3.3 and later · up to and including 6.3.*not affected · semver
    • 6.4 and laternot affected · original_commit_for_fix

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.37-16.1.37-1
Debian:13linuxbefore 6.3.7-16.3.7-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2023-53640Oct 7, 2025 · ASoC: lpass: Fix for KASAN use_after_free out of bounds
    31Monitor
  • ← EarlierCVE-2023-53641Oct 7, 2025 · wifi: ath9k: hif_usb: fix memory leak of remain_skbs
    22Monitor
  • Later →CVE-2023-53644Oct 7, 2025 · media: radio-shark: Add endpoint checks
    22Monitor

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 Linux76ce32682635fe907e0f8e64e039e773e5c7508fVendor (CNA)
Linux Linux90510aed20a26e1a4dede4ef6b640e6a4122f38fVendor (CNA)
Linux Linuxb805d212c394f291f116b12c53401e7ba0c4d408Vendor (CNA)
Linux Linuxe046fe5a36a970bc14fbfbcb2074a48776f6b671Vendor (CNA)
debian:linux6.1.37-1 · Debian:12Package 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.

No history yet (it accumulates with the daily EPSS job).

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).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

—

CVSS vector

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

nvd-primary

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✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (3 more)

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

All records