CVE-2017-5733
published 2026-04-16CVE-2017-5733: UEFI Firmware Parser has a heap out-of-bounds write in tiano decompressor ReadCLen `uefi-firmware` contains a heap out-of-bounds write vulnerability in the…
high7.8
UEFI Firmware Parser has a heap out-of-bounds write in tiano decompressor ReadCLen
`uefi-firmware` contains a heap out-of-bounds write vulnerability in the native tiano/EFI decompressor. in `uefi_firmware/compression/Tiano/Decompress.c`, `ReadCLen()` reads `Number = GetBits(Sd, CBIT)` with `CBIT = 9`, so `Number` can be as large as `511`, while the destination array `Sd->mCLen` has `NC = 510` elements. the loop writes while `Index mCLen[Index++] = 0`.
Reachability is through the normal parsing path: `CompressedSection.process()` -> `efi_compressor.TianoDecompress()` -> `TianoDecompress()` -> `DecodeC()` -> `ReadCLen()`.
Minimum impact is a deterministic crash; depending on build/runtime details, the heap memory corruption may be exploitable for code execution in the context of the parsing process. this project shipped its own copy of the decompressor without the upstream EDK2 hardening for this bug class.
- PR:
- fix commit:
- upstream related fixes: CVE-2017-5731, CVE-2017-5732, CVE-2017-5733, CVE-2017-5734, CVE-2017-5735
Affected
1 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| apple | macos_mojave | — | — |
CVSS provenance
ghsa7.8HIGH
vendor_redhat6.7MEDIUM
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GHSA
UEFI Firmware Parser has a heap out-of-bounds write in tiano decompressor ReadCLen
ghsa·2026-04-16·CVSS 7.8
[HIGH] CWE-787 UEFI Firmware Parser has a heap out-of-bounds write in tiano decompressor ReadCLen
UEFI Firmware Parser has a heap out-of-bounds write in tiano decompressor ReadCLen
`uefi-firmware` contains a heap out-of-bounds write vulnerability in the native tiano/EFI decompressor. in `uefi_firmware/compression/Tiano/Decompress.c`, `ReadCLen()` reads `Number = GetBits(Sd, CBIT)` with `CBIT = 9`, so `Number` can be as large as `511`, while the destination array `Sd->mCLen` has `NC = 510` elements. the loop writes while `Index mCLen[Index++] = 0`.
Reachability is through the normal parsing path: `CompressedSection.process()` -> `efi_compressor.TianoDecompress()` -> `TianoDecompress()` -> `DecodeC()` -> `ReadCLen()`.
Minimum impact is a deterministic crash; depending on build/runtime details, the heap memory corruption may be exploitable for code execution in the context of the parsi
GHSA
UEFI Firmware Parser has a stack out-of-bounds write in tiano decompressor MakeTable
ghsa·2026-04-16·CVSS 7.8
[HIGH] CWE-787 UEFI Firmware Parser has a stack out-of-bounds write in tiano decompressor MakeTable
UEFI Firmware Parser has a stack out-of-bounds write in tiano decompressor MakeTable
`uefi-firmware` contains a stack out-of-bounds write vulnerability in the native tiano/EFI decompressor. in `uefi_firmware/compression/Tiano/Decompress.c`, `MakeTable()` does not validate that bit-length values read from the compressed bitstream are within the expected range (`0..16`). a crafted firmware blob can supply bit lengths greater than `16`, causing out-of-bounds writes to the stack-allocated `Count[17]` array and related decode tables.
reachability is through the normal parsing path: `CompressedSection.process()` -> `efi_compressor.TianoDecompress()` -> `TianoDecompress()` -> `ReadPTLen()` -> `MakeTable()`.
Minimum impact is a deterministic crash; depending on build/runtime details, the stack
Red Hat
edk2: Privilege escalation via heap-based buffer overflow in MakeTable() function
vendor_redhat·2018-10-16·CVSS 6.7
CVE-2017-5733 [MEDIUM] CWE-287 edk2: Privilege escalation via heap-based buffer overflow in MakeTable() function
edk2: Privilege escalation via heap-based buffer overflow in MakeTable() function
[REJECTED CVE] A heap-based buffer overflow vulnerability exists in EDK II within the MakeTable() function of BaseUefiDecompressLib.c, TianoCompress.c, and the UEFI specification. An authenticated attacker could exploit this flaw by supplying a crafted file, potentially leading to privilege escalation.
Package: edk2 (Red Hat Enterprise Linux 8) - Not affected
Apple
CVE-2017-5733: macOS Mojave 10.14
vendor_apple·2018-09-24
CVE-2017-5733 CVE-2017-5733: macOS Mojave 10.14
Apple Security Update: About the security content of macOS Mojave 10.14
Product: macOS Mojave
Version: 10.14
CVE: CVE-2017-5733
Component: Firmware
Impact: An attacker with physical access to a device may be able to elevate privileges
Description: A memory corruption issue was addressed with improved input validation.
No detection rules found.
No public exploits indexed.
Bugzilla
CVE-2017-5733 edk2: Privilege escalation via heap-based buffer overflow in MakeTable() function
bugzilla·2018-10-22
CVE-2017-5733 [MEDIUM] CVE-2017-5733 edk2: Privilege escalation via heap-based buffer overflow in MakeTable() function
CVE-2017-5733 edk2: Privilege escalation via heap-based buffer overflow in MakeTable() function
In EDK II, a vulnerability exists in BaseUefiDecompressLib.c, TianoCompress.c, and UEFI specification via a heap-based buffer overflow in the MakeTable() function. An authenticated attacker could exploit this via a crafted file to escalate privileges.
External Reference:
https://edk2-docs.gitbooks.io/security-advisory/content/edk-ii-tianocompress-bounds-checking-issues.html
Upstream Bug:
https://bugzilla.tianocore.org/show_bug.cgi?id=686
Discussion:
Created edk2 tracking bugs for this issue:
Affects: epel-all [bug 1641452]
Affects: fedora-all [bug 1641451]
---
This issue has been addressed in the following products:
Red Hat Enterprise Linux 7
Via RHSA-2019:2125 https://access.redha
Bugzilla
CVE-2017-5733 edk2: Privilege escalation via heap-based buffer overflow in MakeTable() function [fedora-all]
bugzilla·2018-10-22
CVE-2017-5733 [MEDIUM] CVE-2017-5733 edk2: Privilege escalation via heap-based buffer overflow in MakeTable() function [fedora-all]
CVE-2017-5733 edk2: Privilege escalation via heap-based buffer overflow in MakeTable() function [fedora-all]
This is an automatically created tracking bug! It was created to ensure
that one or more security vulnerabilities are fixed in affected versions
of fedora-all.
For comments that are specific to the vulnerability please use bugs filed
against the "Security Response" product referenced in the "Blocks" field.
For more information see:
http://fedoraproject.org/wiki/Security/TrackingBugs
When submitting as an update, use the fedpkg template provided in the next
comment(s). This will include the bug IDs of this tracking bug as well as
the relevant top-level CVE bugs.
Please also mention the CVE IDs being fixed in the RPM changelog and the
fedpkg commit message.
NOTE: this issue affe
Bugzilla
CVE-2017-5733 edk2: Privilege escalation via heap-based buffer overflow in MakeTable() function [epel-all]
bugzilla·2018-10-22
CVE-2017-5733 [MEDIUM] CVE-2017-5733 edk2: Privilege escalation via heap-based buffer overflow in MakeTable() function [epel-all]
CVE-2017-5733 edk2: Privilege escalation via heap-based buffer overflow in MakeTable() function [epel-all]
This is an automatically created tracking bug! It was created to ensure
that one or more security vulnerabilities are fixed in affected versions
of epel-all.
For comments that are specific to the vulnerability please use bugs filed
against the "Security Response" product referenced in the "Blocks" field.
For more information see:
http://fedoraproject.org/wiki/Security/TrackingBugs
When submitting as an update, use the fedpkg template provided in the next
comment(s). This will include the bug IDs of this tracking bug as well as
the relevant top-level CVE bugs.
Please also mention the CVE IDs being fixed in the RPM changelog and the
fedpkg commit message.
NOTE: this issue affects
2026-04-16
Published