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🛡️ OESA-2023-1121 — shim (CVE-2023-0286)

🟠 CVSS 8.0 — High ✅ No Known Exploit OSV
8.0
CVSS Score
0 Low4 Medium7 High9 Critical10

Description

shim security update

Initial UEFI bootloader that handles chaining to a trusted full bootloader under secure boot environments.

Security Fix(es):

There is a type confusion vulnerability relating to X.400 address processing inside an X.509 GeneralName. X.400 addresses were parsed as an ASN1_STRING but the public structure definition for GENERAL_NAME incorrectly specified the type of the x400Address field as ASN1_TYPE. This field is subsequently interpreted by the OpenSSL function GENERAL_NAME_cmp as an ASN1_TYPE rather than an ASN1_STRING. When CRL checking is enabled (i.e. the application sets the X509_V_FLAG_CRL_CHECK flag), this vulnerability may allow an attacker to pass arbitrary pointers to a memcmp call, enabling them to read memory contents or enact a denial of service. In most cases, the attack requires the attacker to provide both the certificate chain and CRL, neither of which need to have a valid signature. If the attacker only controls one of these inputs, the other input must already contain an X.400 address as a CRL distribution point, which is uncommon. As such, this vulnerability is most likely to only affect applications which have implemented their own functionality for retrieving CRLs over a network.(CVE-2023-0286)

How this vulnerability can be exploited

This issue can be reached over the network, attack complexity is high, an attacker needs no privileges on the target. No user interaction is required. The scope is unchanged, so the impact stays within the vulnerable component. Rated impact: confidentiality high, integrity none, availability high.

CVSS metrics in full

The score comes from this vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H

  • Attack vector: Network — reachable from anywhere that can route to the service.
  • Attack complexity: High — the attacker first has to win a race, learn a secret or otherwise prepare the target.
  • Privileges required: None — an unauthenticated stranger can try it.
  • User interaction: None — nobody has to be tricked into anything.
  • Scope: Unchanged — the damage stays inside the vulnerable component.
  • Confidentiality impact: High — total loss, or loss the attacker controls.
  • Integrity impact: None.
  • Availability impact: High — total loss, or loss the attacker controls.

Affected software

OESA-2023-1121 is recorded against 1 package.

  • shim (fixed in 15.6-9.oe2203sp1)

Timeline and source

Published on 24 February 2023 and last revised on 18 August 2026. No public exploit is currently recorded for this entry. Record sourced from OSV.

References

www.openeuler.org (Advisory)
nvd.nist.gov (Advisory)

Other advisories for this package

shim has other advisories on record. If you are patching this one, these are worth checking on the same host:

Details

Severity HIGH
CVSS Score 8.0
CVSS Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:H
CWE N/A
Public Exploit ✅ No
Source OSV
Published 2023-02-24
Updated 2026-08-20
Modified 2026-08-18
Fix URL N/A

Affected Packages

Software From version Fixed in
shim — 15.6-9.oe2203sp1

Similar Threats

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ⓘ Data Notice: The information presented above has been compiled from publicly available internet sources. Boteraser aggregates this data solely for informational purposes and does not independently classify, evaluate, or endorse any findings about the vulnerabilities listed. The accuracy and completeness of this information is the sole responsibility of the original publishers. Boteraser and its operators accept no liability for any decisions made based on this data.

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