{"answers":{"affected":"3 open source packages ship an affected version, including github.com/axllent/mailpit. It affects 1 product.","exploited":"It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-23829 exists.","fix":"Upgrade github.com/axllent/mailpit to 1.28.3 or later.","what":"CVE-2026-23829 is a medium-severity vulnerability in axllent mailpit, published on 18 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim."},"fix_prompt":"Check this codebase for CVE-2026-23829 and fix it if it is affected.\n\nWhat it is: CVE-2026-23829 is a medium-severity vulnerability in axllent mailpit, published on 18 Jan 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.\nExploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-23829 exists.\n\nAffected packages and fixed versions:\n- github.com/axllent/mailpit (Go): affected all versions; fixed in 1.28.3\n- github.com/axllent/mailpit (Go): affected all versions; fixed in 1.28.3\n- github.com/axllent/mailpit (Go): affected all versions; fixed in 1.28.3\n\nTask:\n1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.\n2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.\n3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.\n4. Run the tests and summarise what changed and why.\n5. If nothing in the project is affected, say so and change nothing.\n\nReference: https://insights.sbomify.com/CVE-2026-23829/ (Markdown: https://insights.sbomify.com/CVE-2026-23829/index.md)","id":"CVE-2026-23829","markdown":"https://insights.sbomify.com/CVE-2026-23829/index.md","name":"CVE-2026-23829","record":{"aliases":["GHSA-54wq-72mp-cq7c","GO-2026-4333"],"analysis":{"component_type":"server_software","fix_type":"upgrade","impacts":["data_modify","other"],"network_reachable":"yes","non_default_config":false,"product_category":"Email testing tool","requires_auth":"none","summary":"Attackers can inject arbitrary SMTP headers or corrupt existing ones in Mailpit by exploiting a regex bypass in address validation.","user_interaction":"not_required","vuln_class":"other"},"analysis_generated_by":"qwen3.8-flash-next","assigner":"GitHub_M","cpe":[{"product":"mailpit","vendor":"axllent"}],"cvss":{"score":5.3,"severity":"medium","source":"cna","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","version":"3.1"},"cwes":[{"id":"CWE-93","name":"Improper Neutralization of CRLF Sequences"},{"id":"CWE-150","name":"Improper Neutralization of Escape, Meta, or Control Sequences"}],"description":"Mailpit is an email testing tool and API for developers. Prior to version 1.28.3, Mailpit's SMTP server is vulnerable to Header Injection due to an insufficient Regular Expression used to validate `RCPT TO` and `MAIL FROM` addresses. An attacker can inject arbitrary SMTP headers (or corrupt existing ones) by including carriage return characters (`\\r`) in the email address. This header injection occurs because the regex intended to filter control characters fails to exclude `\\r` and `\\n` when used inside a character class. Version 1.28.3 fixes this issue.","ecosystems":["Go"],"exploits":{"exploitdb":0,"first_seen":"2026-01-28","github_poc":2,"max_poc_stars":0,"metasploit":0,"nuclei":1,"refs":[{"date":"2026-01-28T03:28:04Z","kind":"github_poc","ref":"https://github.com/SimoesCTT/CTT-Mailpit-RCE-v1.0---Temporal-Resonance-Mail-Server-Takeover","stars":0,"title":"FROM HEADER INJECTION TO FULL RCE DOMINANCE  The Original Flaw (CVE-2026-23829)  · CVSS: 6.1/10 (Medium) - Header injection via regex bypass · Impact: Email spoofing, limited header manipulation · Reality: Boring, basic, barely worth weaponizing  CTT Enhancement Revelation"},{"date":"2026-02-19T01:47:20Z","kind":"github_poc","ref":"https://github.com/SimoesCTT/-CVE-2026-23829-CTT-Mailpit-phase-reconstruction-","stars":0,"title":"It's a CRLF injection in Mailpit's SMTP server — a classic data corruption vulnerability. But under CTT, it's not just a bug. It's a phase reconstruction opportunity."},{"date":null,"kind":"nuclei","ref":"network/cves/2026/CVE-2026-23829.yaml","stars":null,"title":"Mailpit \u003c 1.28.2 - SMTP CRLF Injection"}],"tier":"weaponised"},"has_fix":true,"headline":"Mailpit has SMTP Header Injection via Regex Bypass","id":"CVE-2026-23829","indexable":true,"kev":null,"kind":"cve","links":{"ecosystem":"Go","product":null,"products":[],"type":"other","year":"2026"},"n_packages":3,"n_references":3,"next":{"headline":"SandboxJS has Sandbox Escape via Unprotected AsyncFunction Constructor","id":"CVE-2026-23830"},"packages":[{"ecosystem":"Go","fixed":["1.28.3"],"introduced":["0"],"last_affected":[],"package":"github.com/axllent/mailpit","purl":null,"source":"GHSA-54wq-72mp-cq7c"},{"ecosystem":"Go","fixed":["1.28.3"],"introduced":["0"],"last_affected":[],"package":"github.com/axllent/mailpit","purl":"pkg:golang/github.com/axllent/mailpit","source":"GHSA-54wq-72mp-cq7c"},{"ecosystem":"Go","fixed":["1.28.3"],"introduced":["0"],"last_affected":[],"package":"github.com/axllent/mailpit","purl":"pkg:golang/github.com/axllent/mailpit","source":"GO-2026-4333"}],"prev":{"headline":"Unauthenticated Remote Code Execution via Heap Buffer Overflow in Network Management Service","id":"CVE-2026-23827"},"products":["mailpit"],"published":"2026-01-18","related":[{"cvss_score":7.5,"headline":"Mailpit: Unauthenticated remote memory-exhaustion DoS via unlimited SMTP DATA and /api/v1/send body sizes","id":"CVE-2026-45713","kev_date_added":null,"published":"2026-07-20"},{"cvss_score":6.5,"headline":"Mailpit is vulnerable to Cross-Site WebSocket Hijacking (CSWSH) allowing unauthenticated access to emails","id":"CVE-2026-22689","kev_date_added":null,"published":"2026-01-10"},{"cvss_score":5.9,"headline":"Mailpit: Path traversal \u0026 arbitrary file write in mailpit dump --http via attacker-controlled message IDs","id":"CVE-2026-45711","kev_date_added":null,"published":"2026-07-20"},{"cvss_score":5.9,"headline":"Mailpit: Concurrent map read \u0026 write in proxy CSS rewriter - remote unauth crash (fatal error: concurrent map read and map write)","id":"CVE-2026-45712","kev_date_added":null,"published":"2026-07-20"},{"cvss_score":5.8,"headline":"Mailpit has an incomplete fix for GHSA-6jxm: HTML check still permits SSRF to private/loopback/IMDS via missing IP-filter dialer","id":"CVE-2026-45709","kev_date_added":null,"published":"2026-07-20"},{"cvss_score":5.8,"headline":"Mailpit is Vulnerable to Server-Side Request Forgery (SSRF) via Link Check API","id":"CVE-2026-27808","kev_date_added":null,"published":"2026-02-25"},{"cvss_score":5.8,"headline":"Mailpit Vulnerable to Server-Side Request Forgery (SSRF) via HTML Check API","id":"CVE-2026-23845","kev_date_added":null,"published":"2026-01-19"}],"sources":[{"class":"attribution","licence":"CVE Terms of Use (MITRE)","name":"CVE List","prefix":"CVE"},{"class":"attribution","licence":"CC BY 4.0","name":"GitHub Advisory Database","prefix":"GHSA"},{"class":"attribution","licence":"CC BY 4.0","name":"Go Vulnerability Database","prefix":"GO"},{"class":"attribution","licence":"US public information, NVD API terms","name":"NVD"},{"class":"attribution","licence":"CWE Terms of Use","name":"CWE (MITRE)"},{"class":"attribution","licence":"FIRST CVSS licence","name":"CVSS (FIRST)"},{"class":"attribution","licence":"MIT","name":"Nuclei templates"},{"class":"open","licence":"CC0","name":"PoC-in-GitHub"}],"ssvc":{"automatable":"yes","exploitation":"poc","technical_impact":"partial"},"state":"PUBLISHED","updated":"2026-01-20","vendors":["axllent"]},"summary":"Attackers can inject arbitrary SMTP headers or corrupt existing ones in Mailpit by exploiting a regex bypass in address validation.","url":"https://insights.sbomify.com/CVE-2026-23829/"}