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CVE Record

CVE-2024-43845: udf: Fix bogus checksum computation in udf_rename()

In the Linux kernel, the following vulnerability has been resolved: udf: Fix bogus checksum computation in udf_rename() Syzbot reports uninitialized memory access in udf_rename() when updating checksum of '..' directory entry of a moved directory. This is indeed true as we pass on-stack diriter.fi to the udf_update_tag() and because that has only struct fileIdentDesc included in it and not the impUse or name fields, the checksumming function is going to checksum random stack contents beyond the end of the structure. This is actually harmless because the following udf_fiiter_write_fi() will recompute the checksum from on-disk buffers where everything is properly included. So all that is needed is just removing the bogus calculation.

HighCVSS 7.8Not KEV-listedUpdated
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Glexia's TakeAutomated analysishigh

Security readout for executives and security teams

Plain-English summary

A Linux UDF filesystem rename operation could read uninitialized stack data while calculating a temporary directory-entry checksum. The kernel maintainers describe the calculation as harmless because the checksum is immediately recomputed from complete on-disk data. The faulty calculation was removed.

Executive priority

Address through the normal kernel patch cycle, with faster treatment for multi-user systems using UDF. Although the supplied severity and CVSS are high, the Linux description explicitly calls the faulty checksum harmless. Escalate only if vendor guidance or new exploitation evidence changes that assessment.

Technical view

In udf_rename(), an on-stack iterator contained only fileIdentDesc, but udf_update_tag() checksummed beyond that structure into uninitialized stack contents because implementation-use and name fields were absent. udf_fiiter_write_fi() subsequently recalculated the checksum from complete on-disk buffers, limiting the described practical effect. Stable fixes remove the redundant calculation.

Likely exposure

Exposure requires an affected Linux kernel and local interaction with directory renaming on a UDF filesystem. The supplied affected-version data is ambiguous, listing 6.3, 0, 6.6.44, 6.10.3, and 6.11 without clear range semantics. Confirm applicability through the Linux or distribution advisory and package changelog.

Exploitation context

The CVSS vector describes a local, low-complexity condition requiring low privileges and no user interaction. The source bundle says the operation is actually harmless, and it provides no evidence of exploitation. This CVE is not identified as being in CISA KEV.

Researcher notes

The key issue is an out-of-bounds checksum read over uninitialized stack contents, detected by syzbot. The supplied description says the result is not persisted because the following write recomputes it correctly. No CWE is assigned, and the bundle does not demonstrate disclosure, corruption, code execution, or a practical exploit path.

Mitigation direction

  • Update to a vendor-supported kernel containing the applicable referenced stable fix.
  • Consult the Linux distribution advisory to resolve the ambiguous affected-version information.
  • Prioritize systems allowing untrusted local users to operate on UDF filesystems.
  • Where updating is delayed, limit unnecessary UDF filesystem use according to vendor guidance.

Validation and detection

  • Inventory kernel versions and Linux distribution package revisions across systems.
  • Check distribution changelogs or advisories for CVE-2024-43845 remediation status.
  • Identify hosts using UDF filesystems and permitting untrusted local access.
  • Confirm the installed kernel incorporates the applicable referenced stable commit.
Prepared
Confidence
medium
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

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CVE-2024-43845 mapping review

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Vulnerability profileCVE Program record
Severity
High
CVSS
7.8 (3.1)
Known Exploited
No
Published

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

Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

1CVSS vectors
3Timeline events
1ADP providers
5Source links

SSVC decision data

CISA-ADPCISA Coordinator
Timestamp
Version
2.0.3
Exploitation: noneAutomatable: noTechnical Impact: partial

CVSS vector scores

1 official score

We collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.

ScoreVersionSeverityVectorExploitImpactSource
7.8CVSS 3.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H1.85.9Linux

Vulnerability scoring details

Base CVSS 3.1 score

7.8High
CVSS 3.1 vector shape for CVE-2024-43845Attack VectorAttack ComplexityPrivileges RequiredUser InteractionScopeConfidentiality ImpactIntegrity ImpactAvailability Impact

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

Attack Vector
NetworkAdjacentLocalPhysical
Attack Complexity
LowHigh
Privileges Required
NoneLowHigh
User Interaction
NoneRequired
Scope
ChangedUnchanged
Confidentiality Impact
HighLowNone
Integrity Impact
HighLowNone
Availability Impact
HighLowNone

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

ADP provider summaries

CISA-ADPCISA ADP Vulnrichment
other:ssvc

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinux626860c470ff88e5f7f22a282efd1bfe953a1b54, e9109a92d2a95889498bed3719cd2318892171a2, e9109a92d2a95889498bed3719cd2318892171a2, e9109a92d2a95889498bed3719cd2318892171a2unaffected
LinuxLinux6.3, 0, 6.6.44, 6.10.3, 6.11affected
Weakness

CWE details

No CWE listed

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