Gdb: gdb: stack buffer overflow in parse_tracepoint_definition via stale rs->buf tail
GDB as shipped with Red Hat Enterprise Linux 6, 7, 8, 9 and 10 and Red Hat Hardened Images is exposed when connecting to a remote debug stub that reports tracepoint support. The fix is not listed in the checked facts.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- No fix listed
- Who is exposed
- Specific setups only
Do first: Check whether your setup matches what the bug needs. The remote debug stub reports tracepoint support during the target remote connection handshake GDB as shipped with Red Hat Enterprise Linux
- Last modified
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 35/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Specific setups only
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
GDB, the GNU debugger, has a stack buffer overflow in its client's tracepoint upload handler that lets an attacker-controlled debug stub corrupt stack memory during connection setup. An attacker can reach it remotely without logging in, but a user must take an action to trigger it.
Read the original description
A stack buffer overflow in the GDB client's tracepoint upload handler allows an attacker-controlled debug stub to corrupt stack memory automatically during connection setup. The overflow results from GDB reading beyond the current reply boundary into a stale prior reply in the shared packet buffer.
cve.now Index
- Exploitation?/40Unknown. No CISA SSVC exploitation rating yet
- Exposure12/25Specific setups only, reachable over the network without a login
- Reach10/20Shipped in major Linux distributions
- Severity7.5/10CVSS 7.5
- No patch5/5No patch listed yet
What would change the score
- Would score about 85 if added to CISA KEV
- Would score about 80 if CISA's SSVC rates exploitation active
What to do
Check whether your setup matches what the bug needs.
The remote debug stub reports tracepoint support during the target remote connection handshake GDB as shipped with Red Hat Enterprise LinuxWorkaround: Only connect GDB to trusted debug targets.
Timeline
- CVE published
- First seen by cve.now
Affected versions
- crash
Version range not reported
- gdb
Version range not reported
- gdb
Version range not reported
- gdb
Version range not reported
- crash
Version range not reported
- gcc-toolset-14-gdb
Version range not reported
- gcc-toolset-15-gdb
Version range not reported
- gdb
Version range not reported
Show all 11 packagesShow fewer packages
- crash
Version range not reported
- gdb
Version range not reported
- gdb
Version range not reported
Evidence 2
- Report
- Link
Corrections
None so far.
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Questions about CVE-2026-121995
Is CVE-2026-121995 being exploited?
It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.Source: cve.now feed data
What does this mean?
When GDB connects to a remote debug stub that reports tracepoint support, a malicious stub can overflow a stack buffer in the GDB client during the connection handshake. This corrupts stack memory in the GDB client.Source: access.redhat.com
Am I affected, and how do I check?
The flaw is present in GDB as shipped with Red Hat Enterprise Linux 6, 7, 8, 9 and 10 and Red Hat Hardened Images. It applies when GDB connects to a remote target whose stub reports tracepoint support during the handshake. To check the installed version, run gdb --version.Source: access.redhat.com
How do I fix CVE-2026-121995?
The checked facts do not list a fixed version, so check the Red Hat advisory for the updated GDB package for your release. Until the update is installed, only connect GDB to trusted debug targets.Source: access.redhat.com
What if there's no patch?
Only connect GDB to trusted debug targets, which is the workaround the vendor gives. This limits exposure to the remote stub during connection setup.Source: access.redhat.com