Calling NSS-backed functions that support caching via nscd may call the nscd client side code and in the GNU C Library version 2.36 under high load on x86_64 systems, the client may call memcmp on inputs that are concurrently modified by other processes or threads and crash. The nscd client in the GNU C Library uses the memcmp function with inputs that may be concurrently modified by another thread, potentially resulting in spurious cache misses, which in itself is not a security issue. However in the GNU C Library version 2.36 an optimized implementation of memcmp was introduced for x86_64 which could crash when invoked with such undefined behaviour, turning this into a potential crash of the nscd client and the application that uses it. This implementation was backported to the 2.35 branch, making the nscd client in that branch vulnerable as well. Subsequently, the fix for this issue was backported to all vulnerable branches in the GNU C Library repository. It is advised that distributions that may have cherry-picked the memcpy SSE2 optimization in their copy of the GNU C Library, also apply the fix to avoid the potential crash in the nscd client.
Conclusion & alert: CVE-2026-3904 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.15%). Core evidence: 1 public exploit reference(s) are indexed (Exploit-DB). Mandatory action: Public exploits are available—assess exposure, apply mitigations, and prioritize patching.
Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.
| EDB-ID | Source | Kind | Published | Link |
|---|---|---|---|---|
| — | nvd_ref | exploit_tag | Exploit-DB ↗ |
EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).
| # | Date | Old EPSS score | New EPSS score | Delta (New - Old) |
|---|---|---|---|---|
| 1 | 2026-06-15 | 0.01% | 0.15% | +0.13% |
| 2 | 2026-03-12 | — | 0.01% | — |
Full EPSS history (2 records total)
CVSS metrics for this CVE.
| Base score | Version | Severity | Vector | Exploitability | Impact | Score source |
|---|---|---|---|---|---|---|
| 6.2 | 3.1 | MEDIUM |
|
2.5 | 3.6 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 |
| vendor | priority | summary | link |
|---|---|---|---|
debian
|
unimportant | CVE-2026-3904 unimportant priority: Debian including 1 source packages (glibc), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5. | https://security-tracker.debian.org/tracker/CVE-2026-3904 |
redhat
|
medium | — | https://access.redhat.com/security/cve/CVE-2026-3904 |
suse
|
medium | CVE-2026-3904 severity moderate: SUSE including 17 source package names (glibc, glibc-32bit, …), 175 product×package rows across 20 product lines (SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS, SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS, … (20 product lines)): Known Not Affected 175. | https://www.suse.com/security/cve/CVE-2026-3904/ |
ubuntu
|
medium | CVE-2026-3904 medium priority: Ubuntu including 2 source packages (eglibc, glibc), 12 status rows across 8 suites (bionic, focal, jammy, noble, questing, trusty, upstream, xenial): not-affected 7, DNE 3, needs-triage 2. | https://ubuntu.com/security/CVE-2026-3904 |
| URL | Tags |
|---|---|
| https://sourceware.org/bugzilla/show_bug.cgi?id=29863 | Exploit Issue Tracking Patch |
| https://sourceware.org/git/?p=glibc.git;a=blob_plain;f=advisories/GLIBC-SA-2026-0004;hb=HEAD | Third Party Advisory |
| https://sourceware.org/git/?p=glibc.git;a=commit;h=8804157ad9da39631703b92315460808eac86b0c | Patch |
| https://sourceware.org/git/?p=glibc.git;a=commit;h=b712be52645282c706a5faa038242504feb06db5 | Patch |
| http://www.openwall.com/lists/oss-security/2026/03/11/5 | Mailing List Third Party Advisory |