CVE-2023-25566
GSS-NTLMSSP vulnerable to memory leak when parsing usernames
GSS-NTLMSSP is a mechglue plugin for the GSSAPI library that implements NTLM authentication. Prior to version 1.2.0, a memory leak can be triggered when parsing usernames which can trigger a denial-of-service. The domain portion of a username may be overridden causing an allocated memory area the size of the domain name to be leaked. An attacker can leak memory via the main gss_accept_sec_context entry point, potentially causing a denial-of-service. This issue is fixed in version 1.2.0.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
7.5
GSS-NTLMSSP vulnerable to memory leak when parsing usernames
GSS-NTLMSSP is a mechglue plugin for the GSSAPI library that implements NTLM authentication. Prior to version 1.2.0, a memory leak can be triggered when parsing usernames which can trigger a denial-of-service. The domain portion of a username may be overridden causing an allocated memory area the size of the domain name to be leaked. An attacker can leak memory via the main gss_accept_sec_context entry point, potentially causing a denial-of-service. This issue is fixed in version 1.2.0.
- Record
CVE-2023-25566- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-401
- Updated
- 2026-11-02
EUVDEUVD-2023-29518
7.5
GSS-NTLMSSP is a mechglue plugin for the GSSAPI library that implements NTLM authentication. Prior to version 1.2.0, a memory leak can be triggered when parsing usernames which can trigger a denial-of-service. The domain portion of a username may be overridden causing an allocated memory area the size of the domain name to be leaked. An attacker can leak memory via the main gss_accept_sec_context entry point, potentially causing a denial-of-service. This issue is fixed in version 1.2.0.
- Record
EUVD-2023-29518- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
NVD
7.5
GSS-NTLMSSP is a mechglue plugin for the GSSAPI library that implements NTLM authentication. Prior to version 1.2.0, a memory leak can be triggered when parsing usernames which can trigger a denial-of-service. The domain portion of a username may be overridden causing an allocated memory area the size of the domain name to be leaked. An attacker can leak memory via the main gss_accept_sec_context entry point, potentially causing a denial-of-service. This issue is fixed in version 1.2.0.
- Record
CVE-2023-25566- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-401
- Updated
- 2026-11-02
OSVAZL-43471
7.5
CVE-2023-25566 affecting package gssntlmssp 0.9.0-2
GSS-NTLMSSP is a mechglue plugin for the GSSAPI library that implements NTLM authentication. Prior to version 1.2.0, a memory leak can be triggered when parsing usernames which can trigger a denial-of-service. The domain portion of a username may be overridden causing an allocated memory area the size of the domain name to be leaked. An attacker can leak memory via the main gss_accept_sec_context entry point, potentially causing a denial-of-service. This issue is fixed in version 1.2.0.
- Record
AZL-43471- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVAZL-44997
7.5
CVE-2023-25566 affecting package gssntlmssp for versions less than 1.3.1-1
GSS-NTLMSSP is a mechglue plugin for the GSSAPI library that implements NTLM authentication. Prior to version 1.2.0, a memory leak can be triggered when parsing usernames which can trigger a denial-of-service. The domain portion of a username may be overridden causing an allocated memory area the size of the domain name to be leaked. An attacker can leak memory via the main gss_accept_sec_context entry point, potentially causing a denial-of-service. This issue is fixed in version 1.2.0.
- Record
AZL-44997- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSV
7.5
GSS-NTLMSSP vulnerable to memory leak when parsing usernames
GSS-NTLMSSP is a mechglue plugin for the GSSAPI library that implements NTLM authentication. Prior to version 1.2.0, a memory leak can be triggered when parsing usernames which can trigger a denial-of-service. The domain portion of a username may be overridden causing an allocated memory area the size of the domain name to be leaked. An attacker can leak memory via the main gss_accept_sec_context entry point, potentially causing a denial-of-service. This issue is fixed in version 1.2.0.
- Record
CVE-2023-25566- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-401
- Updated
- 2026-11-02
Show 7 moreShow less
OSVDEBIAN-CVE-2023-25566
7.5
GSS-NTLMSSP is a mechglue plugin for the GSSAPI library that implements NTLM authentication. Prior to version 1.2.0, a memory leak can be triggered when parsing usernames which can trigger a denial-of-service. The domain portion of a username may be overridden causing an allocated memory area the size of the domain name to be leaked. An attacker can leak memory via the main gss_accept_sec_context entry point, potentially causing a denial-of-service. This issue is fixed in version 1.2.0.
- Record
DEBIAN-CVE-2023-25566- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVRHSA-2023:3097
7.5
Red Hat Security Advisory: gssntlmssp security update
- Record
RHSA-2023:3097- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVUBUNTU-CVE-2023-25566
7.5
GSS-NTLMSSP is a mechglue plugin for the GSSAPI library that implements NTLM authentication. Prior to version 1.2.0, a memory leak can be triggered when parsing usernames which can trigger a denial-of-service. The domain portion of a username may be overridden causing an allocated memory area the size of the domain name to be leaked. An attacker can leak memory via the main gss_accept_sec_context entry point, potentially causing a denial-of-service. This issue is fixed in version 1.2.0.
- Record
UBUNTU-CVE-2023-25566- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
OSVALSA-2023:3097 No score
Moderate: gssntlmssp security update
The gssntlmssp is a GSSAPI NTLM mechanism that allows to perform NTLM authentication in GSSAPI programs.
Security Fix(es):
- gssntlmssp: multiple out-of-bounds read when decoding NTLM fields (CVE-2023-25563)
- gssntlmssp: memory corruption when decoding UTF16 strings (CVE-2023-25564)
- gssntlmssp: incorrect free when decoding target information (CVE-2023-25565)
- gssntlmssp: memory leak when parsing usernames (CVE-2023-25566)
- gssntlmssp: out-of-bounds read when decoding target information (CVE-2023-25567)
For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.
- Record
ALSA-2023:3097- Updated
- 2026-11-02
OSVMGASA-2023-0108 No score
Updated gssntlmssp packages fix security vulnerability
Multiple out-of-bounds read when decoding NTLM fields. (CVE-2023-25563) Memory corruption when decoding UTF16 strings. (CVE-2023-25564) Incorrect free when decoding target information. (CVE-2023-25565) Memory leak when parsing usernames. (CVE-2023-25566) Out-of-bounds read when decoding target information. (CVE-2023-25567)
- Record
MGASA-2023-0108- Updated
- 2026-11-02
OSVopenSUSE-SU-2023:0048-1 No score
Security update for gssntlmssp
This update for gssntlmssp fixes the following issues:
Update to version 1.2.0
- Implement gss_set_cred_option.
- Allow to gss_wrap even if NEGOTIATE_SEAL is not negotiated.
- Move HMAC code to OpenSSL EVP API.
- Fix crash bug when acceptor credentials are NULL.
- Translations update from Fedora Weblate.
Fix security issues:
- CVE-2023-25563 (boo#1208278): multiple out-of-bounds read when decoding NTLM fields.
- CVE-2023-25564 (boo#1208279): memory corruption when decoding UTF16 strings.
- CVE-2023-25565 (boo#1208280): incorrect free when decoding target information.
- CVE-2023-25566 (boo#1208281): memory leak when parsing usernames.
- CVE-2023-25567 (boo#1208282): out-of-bounds read when decoding target information.
Update to version 1.1
- various build fixes and better compatibility when a MIC is requested.
Update to version 1.0
- Fix test_gssapi_rfc5587.
- Actually run tests with make check.
- Add two tests around NTLMSSP_NEGOTIATE_LMKEY.
- Refine LM compatibility level logic.
- Refactor the gssntlm_required_security function.
- Implement reading LM/NT hashes.
- Add test for smpasswd-like user files.
- Return confidentiality status.
- Fix segfault in sign/seal functions.
- Fix dummy signature generation.
- Use UCS16LE instead of UCS-2LE.
- Provide a zero lm key if the password is too long.
- Completely omit CBs AV pairs when no CB provided.
- Change license to the more permissive ISC.
- Do not require cached users with winbind.
- Add ability to pass keyfile via cred store.
- Remove unused parts of Makefile.am.
- Move attribute names to allocated strings.
- Adjust serialization for name attributes.
- Fix crash in acquiring credentials.
- Fix fallback to external_creds interface.
- Introduce parse_user_name() function.
- Add test for parse_user_name.
- Change how we assemble user names in ASC.
- Use thread local storage for winbind context.
- Make per thread winbind context optional.
- Fixed memleak of usr_cred.
- Support get_sids request via name attributes.
- Fixed memory leaks found by valgrind.
- Update to version 0.9
- add support for getting session key.
- Add gss_inquire_attrs_for_mech().
- Return actual data for RFC5587 API.
- Add new Windows version flags.
- Add Key exchange also when wanting integrity only.
- Drop support for GSS_C_MA_NOT_DFLT_MECH.
- Record
openSUSE-SU-2023:0048-1- Updated
- 2026-11-02
OSVopenSUSE-SU-2024:12701-1 No score
gssntlmssp-1.2.0-1.1 on GA media
These are all security issues fixed in the gssntlmssp-1.2.0-1.1 package on the GA media of openSUSE Tumbleweed.
- Record
openSUSE-SU-2024:12701-1- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
gssntlmsspAlmaLinux:8 From an advisory covering 5 CVEs |
before 1.2.0-1.el8_8 | 1.2.0-1.el8_8 |
gssntlmsspAzure Linux:2 |
through 0.9.0-2 | None known |
gssntlmsspAzure Linux:3 |
before 1.3.1-1 | 1.3.1-1 |
gss-ntlmsspDebian:12 |
before 1.2.0-1 | 1.2.0-1 |
gss-ntlmsspDebian:13 |
before 1.2.0-1 | 1.2.0-1 |
gss-ntlmsspDebian:14 |
before 1.2.0-1 | 1.2.0-1 |
gssntlmsspMageia:8 From an advisory covering 5 CVEs |
before 1.2.0-1.mga8 | 1.2.0-1.mga8 |
gssntlmsspRed Hat:enterprise_linux:8::appstream From an advisory covering 5 CVEs |
before 0:1.2.0-1.el8_8 | 0:1.2.0-1.el8_8 |
gssntlmssp-debuginfoRed Hat:enterprise_linux:8::appstream From an advisory covering 5 CVEs |
before 0:1.2.0-1.el8_8 | 0:1.2.0-1.el8_8 |
gssntlmssp-debugsourceRed Hat:enterprise_linux:8::appstream From an advisory covering 5 CVEs |
before 0:1.2.0-1.el8_8 | 0:1.2.0-1.el8_8 |
gssntlmsspSUSE:Package Hub 15 SP4 From an advisory covering 5 CVEs |
before 1.2.0-bp154.2.3.1 | 1.2.0-bp154.2.3.1 |
gssntlmsspopenSUSE:Leap 15.4 From an advisory covering 5 CVEs |
before 1.2.0-bp154.2.3.1 | 1.2.0-bp154.2.3.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| affected | ||
| first indexed | CVE List, EUVD, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2023-25566 is a high vulnerability (CVSS 7.5) in Gss-ntlmssp Project Gss-ntlmssp, published February 14, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.10%, the 65th percentile. Fixed in gssntlmssp 1.3.1-1.
References
github.com/gssapi/gss-ntlmssp/security/advisories/GHSA-mfm4-6g58-jw74
github.com/gssapi/gss-ntlmssp/commit/8660fb16474054e692a596e9c79670cd4d3954f4
github.com/gssapi/gss-ntlmssp/releases/tag/v1.2.0
access.redhat.com/errata/RHSA-2023:3097
access.redhat.com/security/cve/CVE-2023-25563
access.redhat.com/security/cve/CVE-2023-25564
Show 46 moreShow less
access.redhat.com/security/cve/CVE-2023-25565
access.redhat.com/security/cve/CVE-2023-25566
access.redhat.com/security/cve/CVE-2023-25567
bugzilla.redhat.com/2172019
bugzilla.redhat.com/2172020
bugzilla.redhat.com/2172021
bugzilla.redhat.com/2172022
bugzilla.redhat.com/2172023
errata.almalinux.org/8/ALSA-2023-3097.html
nvd.nist.gov/vuln/detail/CVE-2023-25566
github.com/CVEProject/cvelistV5/tree/main/cves/2023/25xxx/CVE-2023-25566.json
security-tracker.debian.org/tracker/CVE-2023-25566
advisories.mageia.org/MGASA-2023-0108.html
bugs.mageia.org/show_bug.cgi?id=31574
lists.opensuse.org/archives/list/[email protected]/thread/WXCOTOTL4ZIZB65QEGM65YZZILOED4A3
access.redhat.com/security/updates/classification
bugzilla.redhat.com/show_bug.cgi?id=2172019
bugzilla.redhat.com/show_bug.cgi?id=2172020
bugzilla.redhat.com/show_bug.cgi?id=2172021
bugzilla.redhat.com/show_bug.cgi?id=2172022
bugzilla.redhat.com/show_bug.cgi?id=2172023
security.access.redhat.com/data/csaf/v2/advisories/2023/rhsa-2023_3097.json
cve.org/CVERecord?id=CVE-2023-25563
nvd.nist.gov/vuln/detail/CVE-2023-25563
github.com/gssapi/gss-ntlmssp/security/advisories/GHSA-jjjx-5qf7-9mgf
cve.org/CVERecord?id=CVE-2023-25564
nvd.nist.gov/vuln/detail/CVE-2023-25564
github.com/gssapi/gss-ntlmssp/security/advisories/GHSA-r85x-q5px-9xfq
cve.org/CVERecord?id=CVE-2023-25565
nvd.nist.gov/vuln/detail/CVE-2023-25565
github.com/gssapi/gss-ntlmssp/security/advisories/GHSA-7q7f-wqcg-mvfg
cve.org/CVERecord?id=CVE-2023-25566
cve.org/CVERecord?id=CVE-2023-25567
nvd.nist.gov/vuln/detail/CVE-2023-25567
github.com/gssapi/gss-ntlmssp/security/advisories/GHSA-24pf-6prf-24ch
ubuntu.com/security/CVE-2023-25566
bugzilla.suse.com/1208278
bugzilla.suse.com/1208279
bugzilla.suse.com/1208280
bugzilla.suse.com/1208281
bugzilla.suse.com/1208282
suse.com/security/cve/CVE-2023-25563
suse.com/security/cve/CVE-2023-25564
suse.com/security/cve/CVE-2023-25565
suse.com/security/cve/CVE-2023-25566
suse.com/security/cve/CVE-2023-25567